Cell biology

Salivary gland cell

Salivary gland cell (CL:0009005), any cell of a salivary gland: acinar, ductal, myoepithelial, and supporting cells that produce 0.5–1.5 L saliva daily via calcium-driven chloride and water secretion.

Sanjay Kumar (bioengineer)

Sanjay Kumar is an American bioengineer at UC Berkeley, the E. H. and Mary E. Pardee Professor, known for showing that matrix stiffness regulates brain tumor cell behavior.

Oct 20, 2026

SaOS-2

SaOS-2 (Saos-2, Sarcoma OSteogenic-2), ATCC HTB-85, CVCL_0548, is a human osteosarcoma cell line established in 1973 by Fogh from an 11-year-old girl, with osteoblastic features, high alkaline phosphatase, and homozygous TP53 deletion.

Saponin permeabilization

Saponin permeabilization is a cell biology technique that uses the plant glycoside saponin to open pores in cell membranes so antibodies can enter fixed cells for intracellular staining.

Sarcoplasmic reticulum

Sarcoplasmic reticulum (SR), the muscle-specialized endoplasmic reticulum, stores and releases calcium ions to drive contraction and relaxation; described by Veratti in 1902, rediscovered by electron microscopy in the 1960s.

SCC-15

SCC-15 (SCC15, CVCL_1681, ATCC CRL-1623) is a human tongue squamous cell carcinoma cell line from a 55-year-old man, STR-authenticated, microsatellite stable, with elevated wild-type K-ras and faster growth than SCC-25.

SCC-25

SCC-25, also known as SCC25, is a human cancer cell line derived from a 70-year-old man's tongue squamous cell carcinoma, used widely in oral cancer research.

SCC-4

SCC-4 (SCC4, CVCL_1684, ATCC CRL-1624) is a human tongue squamous cell carcinoma cell line from a 55-year-old male, established by Rheinwald and Beckett, TP53-mutant, used widely in oral cancer, drug response, and radioresistance research.

Oct 20, 2026

SCC-9

SCC-9 (SCC9, CVCL_1685, ATCC CRL-1629) is a human tongue squamous cell carcinoma cell line from a 25-year-old man, established 1981, cisplatin-resistant, TP53-mutant, and widely used in oral cancer research.

Schneider 1

Schneider 1 (S1, CVCL_Z231, RRID:CVCL_Z231) is a spontaneously immortalized Drosophila melanogaster cell line from whole Oregon-R embryos, established by Imogene Schneider in 1972; male, tetraploid, 32-35 hour doubling time, distinct from the S2 and S3 Schneider lines.

Schneider 2

Schneider 2 (S2, SL2, CVCL_Z232) is a Drosophila melanogaster embryonic cell line established by Imogene Schneider (1972 paper; ATCC dates 1969). Hemocyte-like, phagocytic, room-temperature culture without CO2; standard for RNAi screens and recombinant protein expression.

Scolopale cell

Scolopale cell: glia-like support cell of the insect scolopidium (chordotonal organ), homologous to the thecogen cell; surrounds neuron dendrites, forms actin-rich scolopale rods, seals the K+-rich scolopale space, and secretes the dendritic cap.

Scott Robert Manalis

Scott Robert Manalis is an MIT bioengineer and David H. Koch Professor of Engineering who invented the suspended microchannel resonator, a device that weighs single living cells in fluid.

Scramblase

Scramblases are ATP-independent membrane proteins that bidirectionally move phospholipids between bilayer leaflets, exposing phosphatidylserine. Key families: TMEM16 (Ca2+-activated, e.g. TMEM16F) and XKR (caspase-activated, e.g. XKR8).

Scratch assay

The scratch assay, also called the wound-healing assay, measures cell migration by creating a gap in a confluent cell monolayer and imaging cells migrating in to close it.

Seam cell

Seam cells are the lateral epidermal stem cell-like cells of C. elegans, 10 per side at hatching rising to 16, that divide reiteratively during larval development, self-renew, and produce hypodermal, glial, and neuronal daughters before terminal differentiation at adulthood.

Sebocyte

Sebocyte: the specialized lipid-producing epithelial cell of the sebaceous gland (sebaceous gland cell), releasing sebum by holocrine secretion. Defined by androgen/PPARγ regulation, wax ester and sapienic acid output, and roles in acne.

Sec7 domain

Sec7 domain, also called SEC7 homology domain, is a roughly 200-residue catalytic GEF domain for ARF small GTPases, named after yeast SEC7; it has ten alpha-helices, a glutamic-finger catalytic glutamate, and is targeted by brefeldin A.

Second messenger system

Second messenger system: intracellular signaling via cAMP, cGMP, calcium, IP3, and DAG relaying hormone or neurotransmitter signals from cell-surface receptors; founded on Sutherland's cAMP work (1971 Nobel Prize).

Second-harmonic generation microscopy

Second-harmonic generation microscopy, also called harmonic generation microscopy, is a label-free nonlinear optical imaging method that visualizes fibrillar collagen and myosin in intact tissue without stains or dyes.

Secretion assay

A secretion assay is a laboratory method that detects and quantifies molecules secreted by cells, most often cytokines and antibodies, with ELISpot counting secreting cells at single-cell resolution.

Secretome analysis

Secretome analysis is a cell-biology method that identifies and quantifies the set of proteins released by cells into their environment, usually by mass spectrometry of conditioned culture medium.

Secretory cell

Secretory cell (Cell Ontology CL:0000151): a cell specialized in controlled release of substances, spanning endocrine, exocrine, immune, and neuronal types; defined by constitutive versus regulated secretion via secretory granules.

Secretory Pathway

Secretory pathway: the eukaryotic ER-Golgi-trans-Golgi network route delivering proteins to the plasma membrane, lysosomes, or extracellular space via COPII, COPI, and clathrin vesicles; includes regulated, constitutive, and unconventional Golgi-bypassing secretion.

Selective autophagy

Selective autophagy is the branch of macroautophagy in which specific cargos, such as protein aggregates, damaged organelles, and invading bacteria, are tagged with ubiquitin and delivered to the lysosome by autophagy receptors.

Self-replication

Self-replication: a system producing a copy of itself, from semiconservative DNA replication (3 billion base pairs, hours per human cell) to virus hijacking of host cells and synthetic cells like SpudCell.

Senescence-Associated Secretory Phenotype (SASP)

Senescence-associated secretory phenotype (SASP), also called senescence messaging secretome: the pro-inflammatory mix of cytokines (IL-6, IL-8), growth factors, and proteases secreted by senescent cells, driving inflammaging, cancer effects, and targeted by senomorphic drugs.

Sensory neuron

Sensory neuron (afferent neuron): a nerve cell detecting touch, temperature, pain, and other stimuli and carrying information to the CNS; mostly pseudounipolar (DRG) or bipolar (retina, olfactory epithelium), with PIEZO2 as a key mechanotransducer.

Oct 20, 2026

Separation of Sister Chromatids

Separation of sister chromatids: anaphase event in which APC/C degrades securin, activating separase, which cleaves centromeric cohesin (RAD21) so replicated chromosomes segregate to daughter cells.