Translesion synthesis pathways affect (CTG/CAG)100 stability. DF/myc(CTG)100 cells were subjected to the following treatments: nontargeting control siRNA (A, F, and K), nontargeting siRNA and HU (B, G, and L); Rad18 siRNA (C and D); Rad18 siRNA plus HU (E); Pol η siRNA (H and I), Pol η siRNA plus HU (J), Pol κ siRNA (M and N), Pol κ siRNA plus HU (O), and Western blotting (C, H, and M).