The A-ring of vitamin D3 can directly bind to Smo and inhibit HH signal transduction.505 Studies have shown that vitamin D3 can reduce the expression of Gli1 and Ptch and cell proliferation in mouse BCC cell line, and this inhibition is carried out in an independent manner of vitamin D receptor.506 At present, several clinical phase I and phase III trials of vitamin D3 are under way to study the role of vitamin D3 monotherapy or combination therapy in non-Hodgkin’s lymphoma and BCC (NCT03078855, NCT02553447, NCT0343441). Here, SMO is linked to skin basal cell carcinoma.