ARG1 and neoplasm: Notably, highest Mapkapk2 expression was observed in MDSCs within the tumour and correlated with elevated levels of prominent immunosuppressive markers Tgfb1 and Arg1. Comparing expression of these markers in intratumoural MDSCs of WT and MK2ΔCD11c mice, however, revealed no significant effect of CD11c-driven MK2 ablation on the MDSC phenotype itself (Supplementary Fig. 2b).