TI - MEF2A is not retained in the cytoplasm by TGF-beta signalling . AB - In previous studies by De Angelis et al. , TGF-beta was found to induce the re-localisation of MEF2C to the cytoplasm of myogenic cells ( 86 ) . To determine whether MEF2A localisation is dependent on TGF-beta signalling through Smad2 , C2C12 mb were co-transfected with green fluorescent protein ( GFP ) and a dominant negative Smad2 , MADR2 (3SA) ( Fig 6 ) . The phosphorylaTION site of MADR2 (3SA) has three serines substituted with alanines and is known to be able to bind to TGF-beta receptors , but cannot be PHOSphorylated ( 30 ) . After 2 days in growth medium containing 1 ng/ml TGF-beta , it was found that MEF2A is nuclear , while the dominant negative Smad2 is cytoplasmic . This suggests that the MEF2-Smad interaction only occurs when the Smad2 is targeted to the nucleus .