SMAD2 and colorectal cancer: The long arm of chromosome 18 spans several confirmed and putative tumor suppressors, including Retinoblastoma-Binding Protein 8 (RBBP8), SMAD family members 2 and 4 (SMAD2/4), and deleted in colorectal cancer (DCC) (Cunningham et al. 2011;Lim and Pommier 2021).