Steroidogenic Acute Regulatory Protein (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. It is primarily present in steroid-producing cells, including Leydig cells in the testis, theca cells and luteal cells in the ovary and adrenal cells in the adrenal cortex. Due to low levels of pregnenolone, seminomas and Leydig cell tumors display no specific STAR staining. Therefore, STAR antibody may assist in differentiating sex cord stromal tumors (SCST), seminomas and embryonal carcinomas.Primary antibodies are available purified, or with a selection of fluorescent CF® Dyes and other labels. CF® Dyes offer exceptional brightness and photostability. Note: Conjugates of blue fluorescent dyes like CF®405S and CF®405M are not recommended for detecting low abundance targets, because blue dyes have lower fluorescence and can give higher non-specific background than other dye colors.