ATR and leukemia: Therefore, in this study, the significance of DNA damage signaling (MDC1-ATM/ATR-CHEK1 pathway), the telomere topology (ATRX/DAXX), and telomere recruitment to the ALT-associated promyelocytic leukemia nuclear body (APB) (SMC complex and NSMCE2) may have been partly obscured and underestimated due to methodological reasons.