The role of various repair proteins and Cdk2 in MMEJ and HR. (A and C) U2OS cells with single integration of EGFP-MMEJ/HR-MluI substrate and stably expressing Ku70, Mre11, CtIP, Cdk2, BLM, or Exo1 shRNAs or control were assayed as in Fig. 3. (B and D) U2OS (EGFP-HR) or U2OS (EGFP-MMEJ) cells with BLM, Exo1, or H2AX shRNAs or control were induced with I-SceI and assayed.