The ventricular wall of the heart is composed of trabeculated and compactlayers, which are separated by yet unknown processes during embryonic development. Notch signaling plays important roles in cardiac development. Mutations in Notch signaling components are related to human congenital heart diseases Two homologues, Numb and Numblike (Numbl), are expressed in mammals, which also act as inhibitors of Notch signaling. Here we investigate the role of Notch2 and Numb/Numblike during myocardial trabeculation and compaction. The aim of the experiment is to analyze whether Numb/Numblike are involved in inhibition of Notch activity in the developing heart. Since Overexpression of N2ICD phenocoped Numb/Numblike mutants, we performed micoarray using total RNA from aMHC-Cre-mediated overexpression of N2ICD.