To further unravel the function of the CXXC5–CRL4B–NuRD complex in breast cancer development, we used immunohistochemical staining to detect the protein levels of CXXC5, CUL4B, MTA1, and TSC1 in two tissue arrays from breast cancer patients, which consisted of 21 pairs of breast carcinoma samples of grade II and paracancerous tissues, as well as 86 breast carcinoma samples, including grade I (9), II (51), or III (26), from patients with breast cancer. This evidence concerns the gene TSC1 and breast cancer.