This gene encodes a serine/threonine protein kinase that functions upstream of mitogen-activated protein kinase (MAPK) signaling. The encoded protein is cleaved into two chains by caspases; the N-terminal fragment (MST3/N) translocates to the nucleus and promotes programmed cells death. There is a pseudogene for this gene on chromosome X. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Nov 2013].