EDN1 and neoplasm: Similar to our previous observations in vitro, depletion of ET-1 in SOX4-activated cells results in the reduction of angiogenic potential, shown by the decreased capacity to induce ectopic sprouting from the SIV (Figure 5H–J). Taken together, these results indicate that, similar to our in vitro observations, SOX4 controls tumor-induced angiogenesis in vivo, in an ET-1 dependent manner.