S100B and neoplasm: For illustrative purposes, S100B is a marker for malignant melanoma (MM), and one potential mechanism of action for its causal effect on MM is that it binds to the cell cycle regulator, p53, blocking its tumor-suppressive function.172,208–209 Thus, developing S100 protein-specific inhibitors, including for S100B, is of great interest to treat a variety of diseases in which S100B protein levels are elevated.