Rxfp2 is present in putative mesangial cells at embryonic stage 18 (E18) in the rat kidney, suggesting that insulin-like peptide 3 is involved in glomerulogenesis. One of the main regulatory factors in glomerulogenesis is the basic helix-loop-helix transcription factor Pod1. Therefore, we examined the expression of Rxfp2 relative to Pod1 in the fetal and neonatal mouse kidney and tested the hypothesis that Rxfp2 is a downstream target of Pod1. Rxfp2 gene expression in the neonatal kidney was highest at E14 and E16 but decreased significantly at E18. This was not correlated with increased Pod1 expression. However, there was a significant increase in Rxfp2 expression in the kidneys of Pod1(-/-) mice at E18. These data suggest that Pod1 may negatively regulate Rxfp2 expression in the developing glomerulus to promote cell proliferation.