PD 0325901 is a hydroxamic acid ester that is benzhydroxamic acid (N-hydroxybenzamide) in which the hydroxamic acid group has been converted to the corresponding 2,3-dihydroxypropyl ester and in which the benzene ring has been substituted at position 2 by a (2-fluoro-4-iodophenyl)amino group and at positions 3 and 4 by fluorines (the R enantiomer). It has a role as an antineoplastic agent and an EC 2.7.12.2 (mitogen-activated protein kinase kinase) inhibitor. It is a member of propane-1,2-diols, an organoiodine compound, a difluorobenzene, a secondary amino compound, a hydroxamic acid ester and a member of monofluorobenzenes.