miR-21-5p negatively regulates an innate immune receptor, TLR4 (toll-like receptor 4) by targeting the proinflammatory tumor suppressor, PDCD4 (programmed cell death protein 4) [32], as well as directly modulating a key cytokine in immune regulation, IL-12 (interleukin 12). This evidence concerns the gene PDCD4 and neoplasm.