G6PD and breast cancer: Moreover, the levels of immuno-enriched SRC and GSTP1 were lower in human breast cancer samples than in normal tissues when normalized to endogenous G6PD protein controls (Fig. 6A,, C), which is consistent with in vitro data implying that the dynamic G6PD Tyr phosphorylation was related to a changing tripartite complex in response to lactic acid.