To identify the expression level of METTL18 in various subtypes of breast cancer cell lines, the protein levels of METTL18 were examined in MDA-MB-231 (TNBC cell line), MCF-7 (luminal A type cell line), and HER2-enriched cell lines including MDA-MB-453 and SK-BR3. The gene discussed is ERBB2; the disease is breast cancer.