MiR-224 has been reported to be up-regulated in several solid tumors including hepatocellular carcinoma [11, 12], colorectal cancer [13], breast cancer [14], and lung cancer [10], and repressing various targets such as API5, SMAD4, PHLPP1, PHLPP2, RKIP and TNFAIP1. This evidence concerns the gene SMAD4 and lung cancer.