ULK3 is the serine/threonine protein kinase which enhances GLI1 and GLI2 transcriptional activity and consequently positively regulates GLI-dependent SHH signaling. ULK3 may exert this function by promoting GLI1 nuclear localization. ULK3 phosphorylates in vitro GLI2, as well as GLI1 and GLI3, although less efficiently.