SNAI1 and cancer: On the other hand, knockdown of Snail with stable expression of two different sets of short hairpin RNAs (shRNAs) in three cancer cell lines expressing high levels of Snail (HCT116, MDA-231, and SUM149) resulted in a profound induction of 4E-BP1 expression at both the protein and mRNA levels (Fig. 2c, d).