Role in the specific control of proper proliferation of optic lobe neuronal progeny. 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] In ventral nerve cord and supraesophageal ganglion of embryos. Is most prominent in the mushroom body neuropil and the outer proliferation center of the optic lobes in third instar larvae. Isoform A and isoform C are present mainly in embryos and pupae. By contrast, isoform D appears to be expressed most markedly in third instar larvae and pupae. Flies exhibit a specific and marked size reduction of the optic lobes and central brain hemispheres but no major alteration in neuronal architecture can be found. Belongs to the protein kinase superfamily. CMGC Ser/Thr protein kinase family. MNB/DYRK subfamily.