XLX is an IAP family member regulated by phosphorylation during meiosis.

The balance between proliferation and cell death is critical for embryonic development and adult tissue homeostasis. Within an individual cell, coordination of these pathways is aided by direct communication between cell cycle factors and molecules that regulate apoptosis. Here, we show that XLX, a Xenopus laevis inhibitor of apoptosis (IAP) family member, exhibits characteristics typical of an IAP, such as caspase inhibition and autoubiquitylation. However, unlike other IAPs described thus far, we found that XLX is phosphorylated during meiosis by protein kinases that belong to the MAPK and MPF pathways. Finally, we show that caspase-dependent cleavage of XLX is altered when XLX is phosphorylated. In addition to furthering our understanding of the post-translational regulation of an IAP, these findings reveal a novel link between cell cycle-regulated protein kinases and a component potentially involved in apoptosis.