In human squamous cell carcinoma, inecalcitol (a vitamin D analog) induced apoptosis by activating the caspase 8/10-caspase 3 pathway and by inhibiting anti-apoptotic proteins like cellular inhibitor of apoptosis protein-1 (c-IAP1) and X-linked inhibitor of apoptosis protein (XIAP) [26]. This evidence concerns the gene XIAP and squamous cell carcinoma.