1, 4-DPCA is a selective and cell permeable prolyl 4-hydroxylase (P4H) inhibitor. It inhibits α-prolyl4-hydroxylase, an oxygen-sensing enzyme that targets the pro-angiogenic factor HIF-1α for destruction upon hydroxylation of a specific proline residue. It also inhibits asparaginyl-hydroxylase factor inhibiting HIF (FIH) and is useful for controlling excess collagen deposition in pathological fibrosis.