Involved in ciliogenesis (PubMed:32453716). It is required for appropriate acetylation and polyglutamylation of ciliary microtubules, and regulation of cilium length (PubMed:32453716). Acts as a positive regulator of hedgehog (Hh)signaling (By similarity). May participate in the trafficking and/or retention of GLI2 and GLI3 proteins at the ciliary tip (By similarity). Interacts with TOGARAM1, CCDC66, CEP104, CSPP1 and CEP290. Localized to the proximal region in cilia. Stimulation of Hh signaling leads to redistribution of ARMC9 toward the ciliary tip within 6 hours, follow by a gradual return to its original proximal location (By similarity). Localizes to the daughter centriole of the primary cilium in RPE1 cells (PubMed:28625504). Strongly expressed in most melanomas and melanocytes. Weakly expressed in the testis. Up-regulated in response to serum starvation in fibroblasts. The disease is caused by variants affecting the gene represented in this entry. Truncated N-terminus.