AbstractBACKGROUNDMethoxyacetic acid (MAA) causes fetal limb abnormalities when the substance is administrated on gestation day (GD) 11 in mice. Limb abnormalities are caused mainly by extensive cell death in the mesoderm of the limb plate. This investigation focused on identifying a protein that is linked with mouse limb teratogenicity.METHODSA single dose of MAA at 10 mmol/kg body weight was administered by gavage on GD 11; controls were administered vehicle only. Dams were killed by cervical dislocation 4 hr after treatment and forelimb buds were isolated from both the control and treated embryos. Proteins in forelimb buds GD 11 + 4 hr were precipitated out using 40–60% ammonium sulfate and were then analyzed by 2D SDS‐PAGE. Excised protein spots were identified by mass spectrometry and amino acid internal sequence analysis. Identified protein was further confirmed by Western blotting.RESULTSTwo‐dimensional gel analysis indicated that 1 protein spot of 81.7 kDa/pI 7.3 was overexpressed, and the protein matched heat shock protein 70 (HSP70; accession no. P08109, SwissProt).CONCLUSIONSThe results suggest that MAA, when administered to pregnant mice, upregulates HSP70 in the forelimb buds. Birth Defects Research (Part A), 2005. © 2005 Wiley‐Liss, Inc.