NTRK1 and cancer: Table 1 summarizes all the currently known signal transduction mechanisms and their outcomes associated with CD44 molecule in cancer cells. Moreover, CD44v isoforms can also serve as co-receptors with the ability to sequester growth factors (i.e., HGF, FGF, EGF) at the cell surface and presenting them to tyrosine kinase receptor (RTK) complexes (i.e., c-Met, EGFR), which in turn, upon activation, can initiate an appropriate signaling pathway. Figure 4 depicts possible intercellular signaling mediated by the CD44 receptor in cancer cells.