SMAD2 and cancer: Subsequently, a variety of functions linking WNK1 to cancer cell biology have been identified and previously reviewed [34, 35], including activation of extracellular signal-regulated kinase 5 [36], modulation of TGF-β/Smad2 signaling [37], inhibition of autophagy [38], and increasing plasma membrane translocation of GLUT1 and cellular glucose uptake by phosphorylation of the RAB-GAP protein TBC1D4 [39].