Diethyl-pythiDC is an inhibitor of collagen prolyl 4-hydroxylases (CP4Hs). In Vitro Diethyl-pythiDC inhibits CP4H activity in cultured cells at concentrations that do not cause iron deficiency. MDA-MB-231 cells are treated with biheteroaryl dicarboxylates, and assayed for cytotoxicity and indicators of iron deficiency. None of the esterified biheteroaryl dicarboxylates exhibited cytotoxic activity at high micromolar concentrations. Cells treated with dihydroxybenzoate (EDHB demonstrate a strong iron-deficient phenotype. In contrast, cells treated with Diethyl-pythiDC (Diethyl pythiDC) appear to be normal at concentrations as high as 500 μM. Treatment with Diethyl-pythiDC and low levels of diethyl pyimDC does not affect the level of TfR, HIF-1α, or ferritin. MCE has not independently confirmed the accuracy of these methods. They are for reference only. Form:Solid IC50& Target:CP4H