6-methyladenosine (m6A) represents a highly conservedand dynamic modification whose levels vary significantlyacross cellular contexts, developmental stages, and diseasestates.The project reveals that phosphorylation of aconserved serine 399 (S399) residue in the C-terminaldomain of METTL14, a core component of the m6A methyltransferase complex, regulates m6A modification.