FIGURE 6.

The proposed model of EGFR in the regulation of PNPase. A schematic illustrating the regulation of PNPase activity toward c-MYC mRNA by EGFR and DNAPK. Left: in normal condition, PNPase actively regulates the homeostasis of c-MYC mRNA. Right: Exposure to IR increases translocation of EGFR into the nucleus and increases its association with DNAPK and PNPase. EGFR then activates the serine kinase activity of DNAPK toward Ser-776 of PNPase to suppress its ribonuclease activity, leading to increase of c-MYC mRNA. The elevated c-MYC contributes to cell survival and radioresistance.