CD44 and cancer: β-catenin controls the intestinal stem cell (SC) population15 and high β-catenin activity is a functional indicator of cancer stem cells (CSC).16 NF-κB also orchestrates self-renewal signalling in SCs.17 Immununofluorescence microscopy showed that CD44, a downstream target of β-catenin and a major CSC marker, was greatly induced in infected cells (Figure 3a).