CD44 and central nervous system cancer: Proliferation of glioma cells has been correlated to CREB activation [28], and since CD44 signalling is important for sustaining active CREB [29], we analysed the phosphorylation status of S132 in CREB by immunoblotting; dramatically reduced p-CREB levels were detected in CD44 KO clones in comparison to control cells, both in the presence and absence of serum (Figure 1e).