CACNA2D1 and breast cancer: Against GEO data set GSE21422, we verified the expression of PRLR and CACNA2D1 in breast tissue, and found that PRLR was highly expressed in BC tissue, while CACNA2D1 expression was low in BC tissue (p < 0.001), which was consistent with the results of the bioinformatic analysis (Figure 7A and Table 4).