In breast cancer, let-7g, as a tumor suppressor, was found to downregulate the expression of METTL3 by targeting the 3′-UTR of METTL3 mRNA, while hepatitis B virus X-interacting protein (HBXIP) could increase the expression of METTL3 by inhibiting the function of let-7g. Here, METTL3 is linked to neoplasm.