KITLG and central nervous system cancer: Importantly, a subset of these human-derived cytokines that included CXCL10, IL-33, CXCL8, KITLG, CCL2, and TGFα were not secreted or secreted at very low levels in vitro by BT147 cells (Supplementary Fig. 1a), suggesting that the increased secretion was the result of a glioma–host cell interaction within the brain.