The protein encoded by this gene is a member of the serine/threonine protein kinase family.This kinase was shown to be activated rapidly during Fas-mediated apoptosis in Jurkat cells.In response to Fas receptor ligation, it phosphorylates TIA1, an apoptosis-promoting nuclear RNA-binding protein.The encoded protein is a strong inducer of lymphocyte apoptosis.Two transcript variants encoding different isoforms have been found for this gene.Other variants exist, but their full-length natures have not yet been determined.[provided by RefSeq] Synonyms: FAST