In contrast to the immune potentiating effects of CCR2+HSCs, it is very interesting that the CCR2−HSCs that reach the intracranial brain tumor actually upregulate CCR2 expression along with markers of MDSCs including CD11b, Ly6G/C, and F4/80 (Fig. 4c, d and Supplementary Fig. 1). Here, CCR2 is linked to brain neoplasm.