| We have previously demonstrated a novel interaction between merlin and TRBP , which inhibits the oncogenic activity of TRBP . ^^^ In this report , we investigated how merlin inhibits the oncogenic activity of TRBP in association with cell growth conditions . ^^^ In the human embryonic kidney 293 cell line , the level of endogenous merlin increased , whereas that of endogenous TRBP significantly decreased along with the increase in cell confluence . ^^^ The overexpression of merlin decreased the protein level of TRBP , and the ubiquitin like subdomain of merlin ' s FERM domain was important for this activity . ^^^ We also demonstrated that TRBP is ubiquitinylated and the ubiquitinylated forms of TRBP are accumulated by ectopically expressed merlin or cell confluence in the presence of MG 132 , a proteasome inhibitor . ^^^ |