So far, a wide spectrum of ciliary proteins constituting the cilium proteasome have been characterized [26], and among these, some proteins that function in modulating the transduction of cancer-linked molecular signals, such as Smoothened (SMO) [27], Platelet-Derived Growth Factor Receptor (PDGFR) [28] and Vang-like protein 2 (VANGL2) [29] among others, which have been given much attention regarding the role of primary cilia in cancer. Here, SMO is linked to cancer.