Fig 1. A diagram identifying important events in angiogenesis at the cellular level.

Tumor cells secrete VEGF that drives the activation of Endothelial cells by binding to VEGF-receptors on the ECs’ surface. VEGF meditated ECs undertake two distinct phenotypes: tip and stalk cell. Tip cells migrate towards the tumor to reach the VEGF source and highly proliferative stalk cells form the new sprouts body.