STAT3 and central nervous system cancer: Glioma-associated microglia and bone-marrow-derived macrophages account for up to 40% of tumour cellularity and display a transcriptional convergence on colony-stimulating-factor-1 receptor (CSF1R)– and PI3Kγ-dependent pathways that promote STAT3 activation, efferocytosis and matrix remodelling (43, 44).