part of Proteasome mediated protein degradation signaling R-Smad degradation signaling GO:0030579 IEV:0000895 The chemical reactions and pathways resulting in the breakdown of SMAD signaling proteins by ubiquitination and targeting to the proteasome. event ubiquitin-dependent SMAD protein breakdown ubiquitin-dependent SMAD protein catabolic process ubiquitin-dependent SMAD protein catabolism ubiquitin-dependent SMAD protein degradation Negative feedback regulation pathway of TGF beta superfamily signaling by (R-Smad degradation through smurf1/2)