ACTA1 and neoplasm: Recently, Helfrich et al. reported that spontaneously arising MT/ret transgenic melanomas were characterized by a similar distribution of αSMA- and desmin-positive vessels in relation to vascular lumen size and density and found that αSMA-covered large vessels were less sensitive to anti-VEGF therapy [31], thereby illustrating the consequences of tumor vascular heterogeneity for the outcome of antiangiogenic therapy.