Table I.
Functions of S100 proteins
| S100 protein | Localization | Functions | References |
|---|---|---|---|
| S100A1 | Skeletal system, neurons and cardiomyocytes | Functioning of cardiomyocytes and skeletal muscle, regulation of energy metabolism | 19 |
| S100A2 | Cancerous cells | Down regulated in many cancers | 20 |
| S100A3 | Localized in root of hair and some cancerous astrocytes | Differentiation of epithelial cell and hair cuticular barrier formation | 21 |
| S100A4 | Tumorous tissue | Stimulating cell proliferation, mobility and migration | 22 |
| S100A5 | Tumorous tissue | Elevated in bladder cancer cases | 23 |
| S100A6 | Tumorous tissue | Cell cycle progression, cytoskeletal movement and tumour formation | 24 |
| S100A7 | Tumorous tissue | Cytoskeletal functions, adhesion and migration, upregulated in breast cancer | 25 |
| S100A8 | Macrophages, dendritic cells, microvascular endothelial cells | Necessary for embryo implantation, promotes myeloid cells differentiation | 5 |
| S100A9 | Neutrophils, dendritic cells | Inhibits myeloid cells differentiation, induces inflammation | 26 |
| S100A10 | Neutrophils, dendritic cells | Interacts with serotonin receptors and control depression like status | 27 |
| S100A11 | Neutrophils, dendritic cells | Controls cell proliferation and survival | 28 |
| S100A12 | In neutrophils and inducible in macrophages | Regulates VSCM functions | 29 |
| S100A13 | Fibroblasts, osteoblasts and melanoma cells | Regulates secretion factor (FGF)- 1 and IL-1α from various cell types | 30 |
| S100A14 | Tumorous tissue | Inhibits cancer progression via suppression of p53 mediated pathway | 31 |
| S100A15 | ‑ | Acts as an extracellular factor | 32 |
| S100A16 | Tumorous tissue | Disrupts insulin sensitivity and promotes obesity | 33 |
| S100B | Astrocytes, certain neuronal populations, Schwann cells, melanocytes, chondrocytes, adipocytes, skeletal myofibers | Stimulator of cell cycle and migration and an inhibits apoptosis | 34 |
| S100G | Neutrophils, dendritic cells | Maintains cytosolic Ca2+ concentration | 35 |
| S100P | Tumorous tissue | Cell migration and potentially metastasis | 36 |
| S100Z | Tumorous tissue | Down regulated in several tumours | 37,38 |
VSCM, vascular smooth muscle cell; FGF, fibroblast growth factor; IL, interleukin