Established Cell Lines and Claspin Mutants

293T, HeLa, NHDF, HCT116 and U2OS were obtained from ATCC. Claspin flox /- Mouse Embryonic Fibroblasts (MEFs) were established from E12.5 embryos (Yang et al., 2016 (link)). Claspin flox /- MEFs stably expressing the wild-type or AP_DE/A mutant Claspin were established by infecting recombinant retroviruses expressing these cDNAs (Yang et al., 2016 (link)). Cells were grown in Dulbecco’s modified Eagle’s medium (high glucose) supplemented with 15% fetal bovine serum (NICHIREI), 2 mM L-glutamine, 1% sodium pyruvate, 100 U/ml penicillin and 100 μg/ml streptomycin in a humidified atmosphere of 5% CO₂, 95% air at 37°C. HCT-15-Luc#1, NCI-H1975-Luc, NUGC-3 were grown in RPMI supplemented with 10% fetal bovine serum (Gibco); HL-60 were grown in RPMI supplemented with 55 μM β- 2-mercaptoethanol and 10% fetal bovine serum (Gibco); 5K-BR-3-Luc were grown in McCoy’s 5A supplemented with 10% fetal bovine serum (Gibco); KM12-Luc, RPE-1 and TIG-3 were grown in Dulbecco’s modified Eagle’s medium supplemented with 10% fetal bovine serum (Gibco).