Skin-Derived Vitamin D3 Protects against Basal Cell Carcinoma.

UVR in sunlight causes mutations that drive basal cell carcinomas. However, the incidence of these tumors plateaus with prolonged exposure, but the incidence of other skin cancers increases. Makarova et al. now show that vitamin D3 produced in the skin by UVR protects against its oncogenic effects by inhibiting Hedgehog signaling, whereas dietary vitamin D3 does not.