METTL14 and endometrial cancer: R298 of METTL14 is located close to the METTL3/METTL14 junction and catalytic site, and this mutation is frequently found in human endometrial cancer, suggesting the biological relevance of a mutation in the inactive activator of the METTL3/METTL14 complex (14, 15, 16, 37, 52).