Serine/threonine-protein kinase, which may play a role in the response to environmental stress (By similarity). Appears to act upstream of the JUN N-terminal pathway (PubMed:9003777). May play a role in hematopoietic lineage decisions and growth regulation (PubMed:9003777). Able to autophosphorylate (PubMed:9003777). Together with CLNK, it enhances CD3-triggered activation of T-cells and subsequent IL2 production (PubMed:11509653).