Required for the formation of cilia. Plays an indirect role in sonic hedgehog signaling, cilia being required for all activity of the hedgehog pathway (By similarity). Has pro-apoptotic function via its interaction with HIP1, leading to recruit caspase-8 (CASP8) and trigger apoptosis. Has the ability to bind DNA sequence motif 5'-AAAGACATG-3' present in the promoter of caspase genes such as CASP1, CASP8 and CASP10, suggesting that it may act as a transcription regulator; however the relevance of such function remains unclear.