Objective Recent studies indicate ubiquitin-proteasome system particularly the E3 ubiquitin ligase plays a key role in cardiac hypertrophy.We have previously shown that overexpression of Neuregulin receptor degradation protein-1 (Nrdp 1) increased cardiomyocyte injury by inhibiting the target protein of ErbB3 and downstream signaling molecules.In the present study we asked whether overexpression of Nrdp1 might exhibit antihypertrophic effects, and therefore we tested this hypothesis both in vitro.