PDGFRB and colorectal cancer: Our data are consistent with the findings of the phase I clinical trial suggesting enhanced effects of irinotecan when combined with regorafenib in colorectal cancer [25].Intriguingly, PDGFR inactivation was associated with the inhibition of known receptor downstream effectors (i.e. AKT and ERK1/2 pathways) in IGRM57 and may promote the induction of apoptotic cell death as detected by increased PARP-1 cleavage (data not shown) and necrosis.