MKNK1 and diffuse large B-cell lymphoma: However, in the MNK1-TD and MNK1-AA mutants, where MNK phosphorylation cannot be manipulated by p38, eIF4E1-S209 phosphorylation was not affected by p38 inhibitor, further confirming that p38 activity on MNKs and subsequent eIF4E1-S209 phosphorylation is dependent on its ability to phosphorylate MNK, and that p38 activity is upstream to MNKs in DLBCL (Fig. 2h,i).