Parental (i.e., empty vector), BORG-, TRIM28-, or ITGA6-manipulated human and murine breast cancer cells were propagated in 2D- or 3D-culture (Cultrex; Trevigen) for 2 and 6 days, respectively, as described (18 (link),19 (link)). Organoids produced in 3D-cultures were isolated using Cultrex 3D-Culture Cell Harvesting Kit (Trevigen), at which point total RNA was extracted using TRIzol reagent (Thermo Fisher) according to the manufacturer’s instructions. Total RNA (1 μg/reaction) was reverse transcribed with iScript cDNA Synthesis Kit (Bio-Rad) and subjected to semi-quantitative real-time PCR using iQ SYBR Green Supermix (Bio-Rad) as previously described (18 (link)). The primer pairs used are provided in Supplementary Table S2.