TGFB1 and neoplasm: Interestingly, neutrophils in the tumor microenvironment have been associated with angiogenesis in epithelial cancers.30 In order to test possible reversibility of the TGF-β-induced mesenchymal phenotype in vitro, U87 cells were cultured for 4 days with TGF-β and passaged 3 times for 12 days in the absence of TGF-β (supplementary Figures 3a and b).