Role in cell fate determination, required for differentiation of bone marrow stromal cells. Acts downstream of MAP3K7 and HIPK2 to negatively regulate the canonical Wnt/beta-catenin signaling pathway and the phosphorylation and destruction of the MYB transcription factor. May suppress a wide range of transcription factors by phosphorylation of the coactivator, CREBBP (By similarity). Involved in TGFbeta-mediated mesoderm induction, acting downstream of MAP3K7/TAK1 to phosphorylate STAT3.