HIF1A and breast cancer: Palbociclib, a CDK4/6 inhibitor, can suppress HIF-1α and GLUT1 expression, and the combination with BYL719, BKM120, and BEZ235 (PI3K/mTOR inhibitors) can boost synergistic anti-proliferative and pro-apoptotic effects in breast cancer cells and a mouse model [13].