A) Structure of the rationally designed azaindole (IK04). B) The 5 inhibitors of both HCPTP isoforms identified as having IC50 values less than 100 μM at both pH 5 and 7: 30080, 45576, 114792, 128437, and 643735. C) The structures of the additional 6 active inhibitors of HCPTP-A at pH 7: 49848, 65763, 85359, 141566, 210786, and 319095. Compound 45576, which has been determined not to cause aggregation of HCPTP, is boxed for additional emphasis.