SMAD6 and neoplasm: We utilised adenoviruses to efficiently transduce tumour cells with the specific Smad1/5 inhibitor Smad6 (Ad-Smad6-M2 adenovirus) or the Smad1/5 and Smad2/3 inhibitor Smad7 (Ad-Smad7-M2 adenovirus) (Fig. S3A-S3C).