SPP1 and neoplasm: Furthermore, the OPN–CD44 axis in hepatocellular carcinoma CD44+ CSCs mediated hepatitis C virus (HCV) replication and interferon (IFN) signalling as well as the expression of CSCs features, suggesting that this signalling pathway is critical for the propagation and pathogenesis of HCV in CSCs, contributing to CSCs phenotype maintenance and promoting aggressive tumour growth [155].