May function as calcium sensor and modulator, contributing to cellular calcium signaling. May function by interacting with other proteins, such as TPR-containing proteins, and indirectly play a role in many physiological processes. May also play a role in suppressing tumor cell growth. Homodimer. Interacts with FKBP4. Interacts with PPP5C (via TPR repeats); the interaction is calcium-dependent and modulates PPP5C activity. Interacts with TPPP; this interaction inhibits TPPP dimerization (PubMed:33831707). A subset of epithelial cells including normal human mammary epithelial cells and keratinocytes. Preferentially expressed in normal human mammary epithelial cells as opposed to tumor-derived ones. The level of S100L was shown to correlate inversely with tumor progression. By growth factors in early G1 phase and probably by cell-cycle regulation in S phase. DNA methylation probably plays a direct negative role in suppressing S100L gene expression in tumor cells. This protein binds two calcium ions. Belongs to the S-100 family. It is uncertain whether Met-1 or Met-2 is the initiator. Truncated N-terminus.