CD44 signaling enhances CSC-like phenotypes in glioma [24], however, in our experiments, this pathway does not mediate OPN-HIF-1α-driven self-renewal of HCC cells (Figure 7C, 7D) and further research of the role of CD44 signaling in self-renewal of OPN is warranted. The gene discussed is SPP1; the disease is hepatocellular carcinoma.