Figure 6From: Retinoblastoma tumor suppressor pathway in breast cancer: prognosis, precision medicine, and therapeutic interventions CDK4/6 is downstream of multiple pathways. Estrogen receptor (ER) and Her2 as well as many oncogenic mechanisms (for example, phosphatidylinositol 3-kinase) ultimately impinge on the activity of CDK4/6 to drive cell cycle progression. CDK, cyclin-dependent kinase; RB, retinoblastoma tumor suppressor; P, phosphorylated.Back to article page