ERBB2 and breast cancer: In addition, PPARγ was demonstrated to play a crucial role in the maintenance of stemness in ErbB2-positive breast cancer cells; PPARγ antagonist GW9662 induces apoptosis and inhibits tumorsphere formation and tumor formation through the inhibition of lipogenic genes (ACLY, MIG12, FASN, and NR1D1) and stem cell-related genes (KLF4 and ALDH) [71].