Phosphorylates MAP kinase p38. Seems to be active only in mitosis. May also play a role in the activation of lymphoid cells. When phosphorylated, forms a complex with TP53, leading to TP53 destabilization and attenuation of G2/M checkpoint during doxorubicin- induced DNA damage. {ECO:0000269|PubMed:10781613, ECO:0000269|PubMed:17482142}. This is the function of Ensembl gene identifier ENSG00000168078 (PBK, PDZ binding kinase).