Given the interaction between PPAR-α and hormone metabolism, the researchers found that activated PPAR-α increased the expression and activity of CYP1B1 (a subtype of cytochrome P450), further influencing the occurrence and progression of hormone-dependent tumors including breast cancer through the biotransformation of endogenous estrogens and environmental carcinogens (Hwang et al., 2019). The gene discussed is PPARA; the disease is breast cancer.