In response to oxidative stress, a wide variety of stressed tumor cells show increased levels of GSTP1; GSTP1 overexpression was found in many tumors such as esophageal cancer (Joshi et al., 2005), colorectal cancer (Zhang et al., 2014), renal cancer (Kaprilian et al., 2015), lung cancer (Yang, Ebbert, Sun, & Weinshilboum, 2006), and breast cancer (Batist et al., 1986; Huang, Tan, Thiyagarajan, & Bay, 2003; Muftin, AL‐Rubaiꞌe, Yaseen, & Aziz, 2015; Vecanova et al., 2011). Here, GSTP1 is linked to breast cancer.