CRISPR-Cas9 editing efficiencies by various insect U6 promoters in various insect cell lines. (A) S2R-EGFP, (B) Sf9-EGFP, (C) High Five-EGFP, and (D) BmN-EGFP cells were transfected with DmU6:96Ab, SfU6, TnU6-4, and BmU6-2 CRISPR-Cas9 vectors encoding an EGFP-specific sgRNA, selected for puromycin resistance, and EGFP was measured by flow cytometry (the bars show mean fluorescence ± SD, n = 3 per group).