To delineate the contributions of DSB repair pathways (MMEJ, NHEJ and HR) to eccDNA biogenesis, we systematically knocked down key pathway‐specific factors in SKOV3 ovarian cancer cells: LIG3 and POLQ for MMEJ, KU80 and DNA‐PKcs for NHEJ, RAD51 for HR, and PARP1 as an upstream regulator of DNA repair (Figure 2A,B). Here, LIG3 is linked to ovarian cancer.