MRC1 and neoplasm: In summary, we described the efficacy of MSU-42011 in preclinical NF1-deficient models, its ability to reduce pERK levels and tumor-promoting immune cell populations (CD206/CD163 macrophages and FOXP3+ Tregs) and increase activated CD8+ T cells within the tumor and its potential to further decrease tumor burden when combined with an MEK inhibitor, selumetinib.