Furthermore, we found within our GBM single-cell data that there is significant co-expression of Ki-67 with MARCO (p < 0.00001, n = 17,132 cells, chi-squared test; Additional file 3: Fig. S13), suggesting that these MARCO+ macrophages may also be proliferating within the tumor microenvironment. This evidence concerns the gene MKI67 and glioblastoma.