IDO1 and cancer: Overexpression of CaV1.2 or CaV1.3 occurs in many cancers including colorectal, gastric, pancreatic, prostate and breast, and their expression and function can be regulated by estrogen and testosterone, correlating with the high incidence of altered expression of these channels in the female and male reproductive systems.[53] Here, we found that IDO1 expression correlates with that of CaV1.2 and Pyk2 in human breast cancer samples, consistent with the observation that CaV1.2 exerts the regulatory effect on IDO1 transcription by the Pyk2/JAK1/calmodulin complex.