Heat shock proteins (HSP) are a group of highly conserved stress proteins that function primarily as molecular chaperones and are involved in a variety of biological processes including heat resistance, inhibition of apoptosis, regulation of cell development and cell differentiation, and signal transduction. HSP27, also known as HSPB1, is a molecular chaperone in the small molecule heat shock proteome. It is present in many cell types, especially all types of myoblasts, and is overexpressed at different stages of cell differentiation and development.HSP27 is involved in apoptotic signaling pathways and inhibits the activation of procaspase-9. In addition, HSP27 protects actin filaments from fragmentation and also activates proteases.HSP27 may be a potential diagnostic marker, and high levels of HSP27 are present in the serum of breast cancer patients. Phosphorylated HSP27 increases human prostate cancer cell infiltration, promotes cell proliferation and inhibits Fas-induced apoptosis.