When we treated HER2‐positive GC cell lines (MKN1 and YCC38) with the HER2 inhibitor lapatinib, the protein levels of YTHDF1 were significantly reduced, concomitant with decreases in extracellular signal‐regulated kinase (ERK) and protein kinase B (AKT) phosphorylation (Figure 8D). Here, ERBB2 is linked to gastric cancer.