Mnk1 regulates the translation of mRNAs, including cPLA2, in megakaryocytes. Bone marrow megakaryocytes were isolated from WT (n = 3) or Mnk1 KO (n = 3) mice and cultured for 5 days. Ribosomal footprint profiling was performed to identify RNAs with ≥1 ribosomes attached (RPRs), suggestive of mRNAs being actively translated. (A-B) Principal component analysis and heat map showing mRNAs with differentially abundant RPRs. The gene Pla2g4a is enlarged and highlighted with a black arrowhead. (C) Volcano plot showing significantly (false discovery rate < 0.05) upregulated (log₂ fold change > 1.5, red) and downregulated (log₂ fold change < 1.5, green) RPRs in megakaryocytes from WT or Mnk1 KO mice. Blue circles represent RPRs that were not significantly changed in megakaryocytes between WT and Mnk1 KO mice. The gene Pla2g4a is enlarged and highlighted with a red arrow. (D) Bone marrow–derived megakaryocytes from WT and Mnk1 KO mice analyzed for cPLA2 protein expression. β-Actin was used as a loading control. Bar graph shows quantification of total cPLA2 protein in Mnk1 KO megakaryocytes compared with WT megakaryocytes as assessed by densitometry (n = 4 per group, ∗P < .05). (E) Immunoblot of cPLA2 protein after Mnk1 CRISPR-Cas9 (CRISPR Mnk1)-based knockdown in day 13 human CD34⁺-derived cultured megakaryocytes. Guide RNAs not targeting known genes were used as a negative control (Control). Bar graph shows quantification of total cPLA2 protein expression as assessed by densitometry (n = 3 per group, ∗P < .05). NS, not significant.