We hypothesise that despite the observed decrease in blood vessel pericyte coverage in pdgfrβcre+;α6fl/fl mice, the remaining pericytes attached to the endothelial cells provide enough survival factors, for example VEGF and Ang-1 (angiopoietin-1, also known as Angpt1), to allow endothelial cells to survive, allowing for normal tumour angiogenesis and tumour growth. The gene discussed is ANGPT1; the disease is neoplasm.