METTL14 and neuroblastoma: METTL3 is the catalytic component of the METTL3/14 heterodimer, while METTL14 facilitates RNA target binding.19 METTL14 is required for METTL3 to exert effective catalytic function.19 Both METTL3 and METTL14 have functions independent of the methylation activity.20,21 To emulate the mechanism of METTL3/14 inhibition that would be leveraged therapeutically, the small-molecule METTL3 inhibitor STM2457 was used to target catalytic activity of the methyltransferase complex (Figure S7).5 The effect of STM2457 on cell growth was evaluated in eight neuroblastoma cell lines.