PDCD4 and central nervous system cancer: The target of miR-21 are tumor suppressor genes: TPM1 (tropomyosin 1), PDCD4 (programmed cell death 4), SERPINB5 (maspin) in breast cancer and lymphoma models; PTEN in hepatocellular carcinoma and NK/T-cell lymphoma models; TIMP3 (tissue inhibitor of metalloproteinase-3) in glioma models; ANP32A and SMAR-CA4 in B-cell lymphoma models, as well as some members of p53- and TGFβ-associated pathways regulating apoptosis [61].