PPBP and central nervous system cancer: Additional studies have shown that FGL2 secreted by glioma cells activates the downstream signaling pathway Syk/PI3K/AKT/HIF1 by binding to CD16a receptors on the surface of macrophages, thus mediating the release of CXCL7 from macrophages and further promoting the development and progression of glioma of glioma by CXCL7 (Sironi et al., 2006; Bournazos et al., 2016; Yan et al., 2021).