A. DNA ligation was assayed using increasing quantities of DNA Ligase IV/XRCC4 (LX) complex (0, 0.3, 0.6, 1.2, 2.4, and 4.8 pmoles) either incubated with DNA alone (lanes 2–6) or with DNA pre-incubated with HMGA1a (1.2 pmoles, lanes 7–11). The DNA substrate (a double-stranded DNA fragment of 442 bp with 4 bp overhangs) and the ligated DNA multimers of different length were separated in an agarose gel. Lanes 1 and 12 show DNA or DNA/HMGA1a alone as controls, respectively. The figure shows a representative ligation assay. B. Quantification of ligation assay shown in A. The percentage of ligated DNA substrate is plotted as a function of the quantity of DNA Ligase IV/XRCC4 complexes (pmoles).