THBS1 and neoplasm: Some metronomic chemotherapy could induce sustained suppression of circulating endothelial progenitor cells and increase the levels of the endogenous angiogenesis inhibitor thrombospondin 1, both of which could suppress neovascularization.[19] Also, several studies showed the antiproliferative, migration-inhibitory and cytotoxic effects of very low concentrations of chemotherapeutic drugs on various cell types, including fibroblasts, lymphocytes, tumour cells, epithelial cells from various tissues, and microvascular or macrovascular endothelial cells.