miR-21 is activated through gut dysbiosis and targets tumor suppressors PDCD4, BTG2, and TPM1, along with modulating the PI3K/AKT pathway by repressing PTEN to activate ERK and AKT, which induces the downstream NF-κB pathway to release inflammatory cytokines TNF-α, IL-6, and IL-1β [45,51]. Here, PDCD4 is linked to neoplasm.