VEGFA and neoplasm: Fig 2a shows the structure PTC-858, a representative compound identified in the HTS. The results demonstrated that PTC-858 inhibited endogenous VEGF production in tumor cells under hypoxic conditions, but was not cytotoxic (Fig 2b). The IC50 for PTC-858, as determined by VEGF ELISA, is 7.5 nM, while its CC50 is 1700 nM. Thus, the selective index for PTC-858 (CC50/IC50) was greater than 200.