Required for ciliogenesis (PubMed:24797473). Phosphorylates KIF3A (By similarity). Involved in the control of ciliary length (PubMed:24853502). Regulates the ciliary localization of SHH pathway components as well as the localization of IFT components at ciliary tips (By similarity). May play a key role in the development of multiple organ systems and particularly in cardiac development (By similarity). 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). {ECO:0000250|UniProtKB:Q62726, ECO:0000250|UniProtKB:Q9JKV2, ECO:0000269|PubMed:24797473, ECO:0000269|PubMed:24853502}. This is the function of CILK1 (ciliogenesis associated kinase 1, ENSG00000112144).