ERK1/2 substrate CRISPR sgRNA library screen for rare codon-specific regulators

293T cells were infected with CRISPR sgRNA library targeting putative ERK1/2 substrate candidates, then transfected with codon usage-specific GFP/mCherry constructs and BRAFV600E oncogene or luciferase control. FACS sorting was then performed to select populations with high/low GFP/mCherry expression in BRAFV600E-transfected cells versus luciferase-transfected cells. The sgRNAs in selected populations as well as presort populations were amplified and compared to identify regulators that specifically modify the expression of rare codon-enriched fluorophore cDNA constructs.