The MaxDiscovery™ Human Survivin ELISA Test Kit is designed for quantitative determination of the concentration of human Survivin in serum, plasma, and cell culture supernatant. Human survivin, also known as baculoviral IAP repeat-containing protein 5 (BIRC5) and apoptosis inhibitor 4 (API4), is an approximately 34 kDa protein which contains a single baculovirus IAP repeat (BIR) domain and an extended carboxy-terminal a-helical coil that forms a bowtie-shaped homodimer. It has at least two functions, the regulation of cell division and the suppression of apoptosis. Therefore, survivin may play a role in tumor formation and tumor cell resistance to anti-cancer agents. Survivin expression is regulated in a cell cycle-dependent manner. As a component of the chromosomal passenger complex (CPC), survivin has been implicated in the regulation of several mitosis-related events including chromosome alignment, histone modification, and cytokinesis. In addition to its role as a mitotic regulator, survivin also functions as an inhibitor of apoptosis by suppressing cell death initiated by both the intrinsic and extrinsic apoptosis pathways. Since survivin is dramatically over-expressed in many cancers and the expression in these tumors can correlate with an increased rate of tumor recurrence and resistance to therapy, the presence of survivin in urine may also act as a marker for bladder cancer.