Transgenic mouse lines carrying the ERK2 floxed alleles (Samuels et al., 2008 (link)) as well as ERK1 null mice were generated previously (Nekrasova et al., 2005 ; Samuels et al., 2008 (link)). Emx1-Cre and Camk2a-Cre mouse lines were obtained from Jackson Laboratories. All mice were maintained on C57/B6 background. Animals were housed in the Case Western Reserve University (CWRU) Animal Resource Center (ARC) on a 12 hour light-dark cycle, with regular cage changes and ad libitum food and water.