Steroidogenic Acute Regulatory Protein (STAR) (EP226)

Steroidogenic Acute Regulatory Protein (STAR) is a sterol transfer protein that is critical for steroidegenesis.1 Steroidegenesis is the process where steroid hormones are made within specialized cells.2 STAR controls the rate-limiting step of steroidegenesis by translocating cholesterol from the outer mitochondrial membrane to the inner membrane where it is later cleaved to pregnenolone.2 Immunohistochemically, STAR is a cytoplasmic marker that is generally localized in the normal and neoplastic cells of steroid hormone producing tissues such as testis and adrenal gland.3 Due to their low levels of pregnenolone, seminomas and Leydig cell tumors display no specific STAR staining.3 Therefore, this antibody may assist in differentiating sex cord stromal tumors, seminomas and embryonal carcinomas.4