MAPK1 and cancer: In its recombinant form βGBP binds with high affinity (Kd 1.5 × 10-10 M) to approximately 5 × 104 receptors/cell, and at a concentration range of 1 to 20 nM βGBP induces inhibition of cell proliferation via S/G2 cell cycle arrest that, while reversible in normal cells, can lead cancer cells to death through routes that, via downregulation of PI3K activity and suppression of Ras-ERK signalling [32], result in cyclin kinase downregulation, deregulated E2F1 transactivation and apoptosis [41].