THBS1 and neoplasm: In some tumors TSP1 seems to promote tumor progression.(54–56) Other in vivo and clinical studies have shown an inverse correlation between TSP1 expression, malignancy and poorer prognosis.(57,58) When mice carrying the oncogene neu/erbB2 were crossed with TSP1 null mice, the number of mammary tumors and angiogenesis increased.