Validated target for mir-21 include TPM1, PDCD4, and PTEN [50–53] and recently mir-21 overexpression was indeed associated with the acquired resistance of EGFR-TKI in NSCLC, due to the activation of PI3K/AKT pathway through PTEN and PDCD4 inhibition by mir-21 [54]. Here, PDCD4 is linked to non-small cell lung carcinoma.