Culturing Bra-GFP/Rosa26-E2C and GFP-KSCs

Bra-GFP/Rosa26-E2C mESCs (Zhou et al., 2018 (link)) were maintained in 0.1% gelatinised six-well tissue culture plates with mitomycin-C (Sigma-Aldrich, M4287) inactivated STO (ATCC, SCRC-1049) feeder cells at 37°C in a humidified incubator with 5% CO₂ in Dulbecco's modified Eagle's medium (DMEM) (Sigma-Aldrich, D6546) supplemented with 15% fetal bovine serum (FBS) (Sigma-Aldrich, F2442), 1% minimum essential medium (MEM) non-essential amino acid (Sigma-Aldrich, M7145), 2 mmol l⁻¹ L-glutamine (Sigma-Aldrich, G7513), 0.1 mmol l⁻¹ β-mercaptoethanol (Gibco, 31350) and 1000 U ml⁻¹ mouse leukaemia inhibitory factor (mLIF) (Merck Millipore, ESG1107). Cells were passaged every other day and those at passage 13–22 were used for experiments.
GFP-expressing mouse neonatal kidney-derived stem cells (GFP-KSCs) (E. Ranghini, PhD thesis, 2011) were maintained in 60-mm tissue culture dishes at 37°C in a humidified incubator with 5% CO₂ in DMEM supplemented with 10% FBS (Gibco, 10270), 1% MEM non-essential amino acid (Sigma-Aldrich, M7145), 2 mmol l⁻¹ L-glutamine (Sigma-Aldrich, G7513) and 0.1 mmol l⁻¹ β-mercaptoethanol (Gibco, 31350). Cells were passaged 2–3 times per week and those at passage 17–20 were used for experiments.