Dual-specificity kinase with both serine/threonine and tyrosine kinase activities (PubMed:8038606). Required for postmeiotic development of microspores (Ref.2). Involved in embryo sac development at the late stages of megagametogenesis (Ref.3). Involved in the phosphorylation of KIP1 (PubMed:11500547). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Interacts with KIP1. Expressed in mature pollen grains and pollen tubes, but not in style, petal, leaf, root or sepal (PubMed:8038606, PubMed:11500547). Very low expression in the ovary (Ref.3). Detected around the time of microspore mitosis with a peak in mature pollen grains. Autophosphorylated. Belongs to the protein kinase superfamily.