SMAD2 and colorectal carcinoma: The results showed that the protein expression levels of SMAD1 and SMAD2 were significantly increased in CRC tissues (Figures 4(a) and 4(b)), the protein expression levels of SMAD3, SMAD4, and SMAD5 were significantly decreased in CRC tissues (Figures 4(c)–4(e)), and the protein expression levels of SMAD7 was not significantly different (Figure 4(f)).