SPARCL1 and glioblastoma: Neural G0 includes many genes known to participate in neurogenesis or glioma biology: including: CLU, a secreted antiapoptotic factor36; F3, a marker of quiescent GBM cells37; PTN and its target PTPRZ1, which promote stemness, signaling, and proliferation of neural progenitors and glioma tumor cells38–41; S100B, a chemoattractant for tumor-associated macrophages in glioma42,43; and SPARC and its ortholog SPARCL1, which promote brain tumor invasion and survival44–46; and TTYH1, required for NSC stemness and Notch activation47,48 (Fig. 2g, h).