PDCD4 and non-small cell lung carcinoma: It has been proven that miR-21 stimulates cell growth and the invasion of NSCLC cells by targeting PTEN (Phosphatase and tensin homolog), enhancing the RAS/MEK/ERK pathway through their negative regulators repression (Spry1, Spry2, Btg2, Pdcd4) and repressing the expression of several pro-apoptotic proteins such as Apaf1, FasL, RhoB, Pdcd4 [62-65].