Growth factor signaling leads to the induction or repression of immediate early genes, but how these genes act collectively as effectors of downstream processes remains unresolved. We have used gene trap–coupled microarray analysis to identify and mutate multiple platelet-derived growth factor (PDGF) intermediate early genes in mice. Mutations in these genes lead to a high frequency of phenotypes that affect the same cell types and processes as those controlled by the PDGF pathway. We conclude that these genes form a network that controls specific processes downstream of PDGF signaling.