Studies using ex-vivo models have reported that the microvasculature regulates the quiescent state of breast cancer cells, and that expression of thrombospondin (TSP-1) by the stable microvasculature supports dormancy whereas pro-tumourigenic molecules (like periostin and TGF-b1) produced during vessel sprouting stimulates tumour cell proliferation [26]. This evidence concerns the gene TGFB1 and breast cancer.