CACNA2D3 and prostate cancer: In support of a direct role for α2δ-2 in prostate cancer development, gabapentin, an inhibitor of α2δ subunits, was capable of inhibiting tumor development in xenografts [40].** In contrast, the CACNA2D3 gene, which encodes for α2δ-3, has been identified as a methylation site in gastric cancer.