Fig. 1: DDB2 negatively regulates the conversion of non-CSCs to CSCs in ovarian cancer cells.

a Schematic outline of the experimental procedure in Tet-inducible DDB2 knockdown cells (2008-pTRIPZ-shDDB2). b Sorting of CD44⁻CD117⁻ cells (blue) from 2008-pTRIPZ-shDDB2-c1 cells. c–f CD44⁻CD117⁻ cells were cultured in the absence or presence of Dox for 12 days, DDB2 expression was determined using immunoblotting (c), the percentage of CD44⁺CD117⁺ cells was determined using FACS (d), the sphere formation ability was determined using the sphere-forming assay (e). N = 3, Bar: SD, **P < 0.01. The frequency of tumor-initiating cells (TICf) was quantified by a xenograft assay with limiting dilution, and calculated using the ELDA software (f). g Schematic outline of the experimental procedure in Tet-inducible DDB2 overexpression cells (SKOV3-pTRE3G-DDB2). h Sorting of CD44⁻CD117⁻ cells (blue) from SKOV3-pTRE3G-DDB2 cells. i, j CD44⁻CD117⁻ cells were cultured in the presence or absence of Dox for 12 days, DDB2 expression was determined using immunoblotting (i), the percentage of CD44⁺CD117⁺ cells was determined using FACS (j). N = 3, Bar: SD, **P < 0.01