RECQ1 regulates the DNA2-dependent degradation of stalled forks. (A) Representative IdU tracts in RECQ1-depleted U-2 OS cells during different exposure time to HU (out of 2 repeats; n ≥ 350 tracts scored for each dataset). (B) Bar graph represents the mean values of each time point from Figs. 1 C and 2 A. (top) RECQ1 expression after shRNA knockdown. (C, D, and E) Representative IdU tracts in RECQ1-, DNA2-, or RECQ1/DNA2-codepleted U-2 OS cells in the presence of HU (C), CPT (D), and MMC (E; out of 2 repeats; n ≥ 300 tracts scored for each dataset).(top) RECQ1 and DNA2 expression after shRNA or siRNA knockdown. (F) Representative IdU tracts in RECQ1-depleted U-2 OS cells complemented with shRNA-resistant WT RECQ1 (WT) or ATPase-deficient (K119R) RECQ1 (out of 2 repeats; n ≥ 325 tracts scored for each dataset). (top) Expression of Flag-tagged RECQ1-WT and RECQ1-K119R in RECQ1-depleted cells.