NIPBL-deficient cells display increased DNA damage sensitivity. (A) Schematic representation of NIPBL (not to scale) with approximate localization of conserved motifs, and relative positioning of mutations identified in the CdLS patients included in this study. (B) LCLs from healthy controls and CdLS patients (P1-P3 and P5 had defined NIPBL mutations), as well as LCLs from patients deficient for ESCO2 (RBS) or ATM (AT) were exposed to γ-IR at indicated dosages, and survival was monitored after three population doublings using the MTS assay. Doubling times and significant differences in survival are indicated in Table 1. (C) FBs from patients deficient in NIPBL (P7 and P10), Cernunnos, or control FBs were exposed to γ-IR at indicated dosages and analyzed for survival by the colony formation assay. (D) Control FBs were transfected with control (siCTRL) or NIPBL siRNA (siNIPBL) and exposed to γ-IR at indicated dosages and analyzed for survival by the colony formation assay. (B–D) An average from ≥3 experiments for each cell type is shown, and error bars indicate SD. (E) Protein extracts were isolated from control FBs 48 h after transfection with siCTRL or siNIPBL, but before exposure to γ-IR for the colony formation assay shown in D, and were run on SDS gels. (F) Control FBs were transfected with siCTRL or siNIPBL, and 48 h after transfection and at indicated time points after exposure to γ-IR, protein extracts were isolated and run on SDS gels. (E and F) Indicated proteins were detected by Western blotting. Representative gels from three independent experiments are shown.