Cell biology

Expansion microscopy

Expansion microscopy (ExM) is a sample preparation method that embeds fixed cells and tissues in a swellable polymer gel, enlarging them so nanoscale structures become resolvable on conventional microscopes. It was first published in 2015.

Explant culture

Explant culture is a cell culture method in which a tissue fragment is placed in growth medium, either to derive primary cells or to preserve tissue architecture.

Extracellular matrix

Extracellular matrix (ECM): the protein and polysaccharide network between cells, including collagens, fibronectin, laminins, and proteoglycans, that supports tissue structure, signals through integrins, drives wound healing, and underlies ECM-based biomaterials.

Extracellular matrix organization

Extracellular matrix organization (GO:0030198; Reactome R-HSA-1474244): the cellular process of assembling, arranging, and disassembling the ECM of collagens, elastin, fibronectin, laminins, and proteoglycans, remodeled by MMPs and ADAMTS.

Oct 20, 2026

Ezrin/radixin/moesin

Ezrin/radixin/moesin (ERM) proteins are three homologous metazoan linkers tethering the actin cytoskeleton to the plasma membrane via a FERM domain, activated by PIP2 binding and threonine phosphorylation, with tissue-specific roles in polarity, immunity, and cancer.

F-actin binding

F-actin binding: association of proteins with filamentous actin, the actin cytoskeleton polymer. Binding sites for eight filament-binding classes mapped by EM plus crystallography; CH-domain ABDs, capping, severing, cross-linking proteins.

Facilitated diffusion

Facilitated diffusion (facilitated transport, carrier-mediated diffusion): passive membrane transport through channel or carrier proteins (GLUT uniporters, ion channels) down the electrochemical gradient, saturating at Vmax with no ATP use.

FADD

FADD (Fas-associated via death domain) is a 208-amino-acid adaptor protein with N-terminal DED and C-terminal DD domains that assembles the death-inducing signaling complex, recruiting caspase-8/10 to death receptors like Fas, TRAILR, and TNFR1, and also regulates cell cycle, necroptosis, and tumor immunity.

FaDu

FaDu (CVCL_1218, ATCC HTB-43) is a human hypopharyngeal squamous cell carcinoma cell line established in 1968 from a 56-year-old male patient from Calcutta, India; a standard HNSCC model with CDKN2A and TP53 mutations used in cisplatin, radiation, and 3D culture studies.

Farage

Farage (CVCL_3302, ATCC CRL-2630) is a human EBV-positive B lymphocyte cancer cell line established in 1990 from a 70-year-old woman with diffuse large B-cell lymphoma; it produces no immunoglobulin and is a PMBL-related research model.

Fas ligand

Fas ligand (FasL, CD95L, CD178, FASLG) is a 40 kDa type II transmembrane TNF-family ligand binding Fas/CD95; membrane-bound form drives apoptosis, inflammation, and immune privilege, while shed soluble FasL is largely antagonistic.

Fascin

Fascin (FSCN1), a 55 kDa globular monomeric actin-bundling protein with four β-trefoil domains, cross-links actin into tight ~8 nm-spaced parallel bundles in filopodia; overexpressed in metastatic cancer, targeted by phase 2 inhibitors.

FASTKD2

FASTKD2 (FAST kinase domain-containing protein 2, mitochondrial) is a mitochondrial matrix RNA-binding protein binding 16S rRNA and MT-ND6, required for mitoribosome assembly; biallelic mutations cause COXPD44 mitochondrial encephalomyopathy.

Fat body cell

Fat body cell: the principal cell (trophocyte) of the insect fat body, an adipose- and liver-like tissue storing lipids, glycogen, and proteins, mediating immunity and detoxification, and signaling to the brain; distinct from mammalian adipocytes.

Fatal infantile cytochrome C oxidase deficiency

Fatal infantile cytochrome C oxidase deficiency, or fatal infantile COX deficiency, is a very rare mitochondrial disease in which defective complex IV causes fatal cardioencephalomyopathy in infancy.

Oct 20, 2026

Fenestrated endothelial cell

Fenestrated endothelial cell (window cell, CL:0000666): an endothelial cell with 50-80 nm transcellular pores (fenestrae), usually diaphragmed via PLVAP, lining filtration and secretion beds such as kidney glomeruli, choroid plexus, gut mucosa, and endocrine glands.

Fetal cardiomyocyte

Fetal cardiomyocyte (CL:0002495; embryonic or neonatal cardiomyocyte): a proliferating, mononucleated heart muscle cell not yet terminally differentiated; it builds the fetal heart by hyperplasia before maturing via binucleation, isoform switching, and oxidative metabolism.

Fibroblast

Fibroblast: connective tissue cell secreting collagen-rich extracellular matrix; also called fibrocytes when quiescent. Term coined by Ziegler 1895; differentiates into contractile myofibroblasts during wound healing; profoundly heterogeneous across organs.

Fibronectin

Fibronectin: dimeric adhesive glycoprotein of blood, cell surfaces, and extracellular matrix; RGD motif, α5β1 integrin receptor, stretch-driven fibrillogenesis, wound healing, and bacterial FnBP target.

Fibrous astrocyte

Fibrous astrocyte (Cell Ontology CL:4042008), a white-matter astrocyte subtype with long straight processes parallel to axon bundles; GFAP domain diameter 85.6 μm in mouse, 183.2 μm in human; supports axon tracts and contacts vasculature and nodes of Ranvier.

Fibulin-1

Fibulin-1 (FBLN1, Gene ID 2192) is a 90-100 kDa extracellular matrix glycoprotein, the first-discovered fibulin, found in plasma, basement membranes, and elastic fibers, with splice variants C and D, roles in fibronectin-dependent matrix assembly, vessel stability, and lung, cancer, and liver disease.

Filaments in between nuclei protein-1

Fin1 (Filaments in between nuclei protein 1, FIN1/YDR130C) is a budding yeast coiled-coil protein forming cell cycle-specific 10 nm filaments between spindle pole bodies, a PP1/Glc7 regulatory subunit at spindles and kinetochores, distinct from fission yeast fin1 kinase.

Five prime untranslated region

The 5′ UTR (five prime untranslated region) is the mRNA segment between the cap and start codon that governs translation initiation via Kozak context, uORFs, secondary structure, IRESs, and riboswitches, and is engineered in mRNA therapeutics.

Flagellum

Flagellum: hairlike motility appendage in three unrelated forms. Bacterial flagella rotate via an ion-powered ~45 nm motor; archaea use type IV pilus-related archaella (renamed 2012); eukaryotes use beating 9+2 axoneme flagella with dynein.

Fluid mosaic model

Fluid mosaic model: Singer and Nicolson's 1972 model of cell membranes as a fluid phospholipid bilayer with embedded amphipathic proteins; later updated with lipid rafts, cytoskeletal fences, and protein crowding.

Fluorescence lifetime imaging microscopy

Fluorescence lifetime imaging microscopy (FLIM) maps the decay time of fluorescence from every pixel of labeled cells or tissue, enabling FRET measurements, metabolic imaging, and clinical tissue sensing.

Fluorescence loss in photobleaching

Fluorescence loss in photobleaching (FLIP) is a live-cell microscopy technique in which a small region is bleached repeatedly with a laser, revealing how proteins diffuse and move between cellular compartments.

Fluorescence Microscopy

Fluorescence microscopy images fluorophore-labeled specimens by detecting longer-wavelength emitted light; spans widefield, confocal, TIRF, two-photon, light sheet, and super-resolution modalities with distinct resolution, depth, and speed trade-offs.

Fluorescence polarization microscopy

Fluorescence polarization microscopy is a fluorescence technique that measures emission polarization pixel by pixel to map the orientation, clustering, and rotational mobility of labeled biomolecules in cells.