THBS1 and neoplasm: Interestingly, we also observed that SN-38 determined the significant increase of TSP-1 in conditioned medium of microvascular endothelial cells after 72 h of treatment, a change closer to the beginning of low-concentration therapy, and an inhibition of phosphorylation of Akt; these two observations may be mechanistically linked as demonstrated by Bussolati et al (2006), who described the modulatory role of Akt on TSP-1 synthesis in tumour endothelial cells (TEC).