Since, as mentioned, VDR/RXR was found to be functional in inducing GPRC5A expression, the aim of this work was to determine whether VD (cholecalciferol, which is intracellularly converted to its active form 1,25(OH)2D or VD3) can modulate GPRC5A expression in the Caco-2 and T84 colon carcinoma cells, and whether PKC is involved in this regulation. Here, GPRC5A is linked to colon carcinoma.