We recently reported that subpopulations of tumour-derived endothelial cells (TECs) are heterogeneous in their ability to differentiate into SMA+ CAF-like cells after TGFβ stimulation.13,21,22 Because normal fibroblasts will spontaneously gain CAF markers upon in vitro culture, we reasoned that some of these TEC precursors, being absent for SMA and other CAF markers even after in vitro propagation, would be a useful tool for studying how non-CAFs are converted to CAFs by TGFβ. The gene discussed is TGFB1; the disease is neoplasm.