PC and breast carcinoma: Furthermore, high expression of PC in breast cancer has been shown to affect tumor proliferation and metastasis, while PC expression was increased in lung metastases of breast cancer compared with the primary site, and knockdown of PC decreased NADPH/NADP+ ratios compared with untreated control cells and increased the sensitivity of breast cancer cells to H2O2 treatment, indicating that PC protected against reactive oxygen species (ROS) in tumor cells [26].