An scQer library of five promoters (n = 1,122 unique oBC–promoter–mBC triplets, median 205 mBC–oBC pairs per promoter) was integrated in three human cell lines (HepG2, K562 and HEK293T) at high multiplicity via piggyBac. Following integration, bottlenecking and expansion, clonal cells were (1) separately subjected to bulk MPRA and (2) mixed at 1:1:1 ratio and single-cell profiled.
