Finally, we visualizedPtpn11E76K/+ stem cells and surroundingcells in tasquinimod- or vehicle-treated mice and found that the distance between theseleukemia-initiating cells(CD150+CD11b−Ly6G−CD3−B220−Ter119−CD48−)(cyan) and the closest PMN-MDSCs (CD11b+Ly6G+) (yellow) wassignificantly increased following tasquinimod treatment (Fig. 8Q), confirming that the recruitment of PMN-MDSCs to the microenvironmentof Ptpn11 mutant stem cells was attributed to S100a9/S100a8 overexpressedby these leukemia-initiating cells. This evidence concerns the gene S100A9 and leukemia.