CYP24A1 and melanoma: However, cell culture studies on rodent melanomas have shown a complex effect of melanin pigmentation on vitamin D signaling, with cells showing moderate levels of pigmentation being sensitized to the antiproliferative effects of vitamin D hydroxyderivatives in comparison to the amelanotic phenotype, but with heavy melanization levels leading to reduced expression of the VDR, RXR, CYP24A1, and PDIA3 mRNA and a decrease of the ligand-induced VDR translocation to the nucleus [410].