Chemical structures of inhibitors for HIF-1 signaling pathway. A. Four representative inhibitors from the qHTS. NCGC00044926 is a representative from series 31, NCGC00043898 and NCGC00049606 from series 39 and NCGC00056044 from series 71. B. Number of active and inactive compounds containing the 5-thiophen-1,2,4-oxadiazole core versus the 1,2,4-oxadiazole core. The thiophen-oxadiazole core appears to be important for compound activity. Right, Leadscope Maximal Common Substructures (MCS) used to populate series 31 and 39.