Required for ciliogenesis, particularly in neuronal and retinal progenitor cells (By similarity). Phosphorylates KIF3A (By similarity). Involved in the control of ciliary length (By similarity). Regulates the ciliary localization of SHH pathway components as well as the localization of IFT components at ciliary tips (By similarity). May play a role in cardiac development (PubMed:8570168). Regulates intraflagellar transport (IFT) speed and negatively regulates cilium length in a cAMP and mTORC1 signaling-dependent manner and this regulation requires its kinase activity (By similarity). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Also found at the ciliary tip. Expressed in embryonic heart from day 11. Highly expressed in the uterus and at lower levels in brain, heart, lung, kidney, skeletal muscle, ovary and liver in adult tissues. Autophosphorylated on serine and threonine residues (PubMed:8570168). Phosphorylation at Thr-157 increases kinase activity (By similarity). Belongs to the protein kinase superfamily. CMGC Ser/Thr protein kinase family. CDC2/CDKX subfamily.