We observed that, at 10 d.p.i., CCR2+ immune cells infiltrated the brains of tumor mice and accumulated in the VI (Figure 5C) Interestingly, a large percentage of neutrophils in the VI were CCR2+ (Figure 5D), which infiltrated throughout the VI and often formed large aggregates consisting of 20 cells or more (Figure 5—figure supplement 1A). This evidence concerns the gene CCR2 and neoplasm.