B2M and breast cancer: Correlation analysis showed that β2M had a positive correlation with p-CREB (r = 0.250, p = 0.043), p-SGK1 (r = 0.310, p = 0.011), and Bcl-2 (r = 0.326, p = 0.007) and had no correlation with HIF-1α, VEGF, and p-ERK1/2 (p > 0.05) in cancer tissues of patients with luminal A breast cancer.