FEN1 and central nervous system cancer: To confirm this conclusion, we also analyzed fork degradation upon effective FEN1 and DNA-PKcs depletion by treating two additional glioma cell lines, U251 and U87MG cells, with the FEN1 inhibitor sc-13 [41] and the DNA-PKcs inhibitor NU-7441[51], which can be used both in vitro and in vivo.