To directly dissect the paralog synthetic lethal relationship of MFRN1 and MFRN2, we next designed potent sgRNAs targeting each gene (see Additional file 1: Fig. S3a for guide validation) and used them for genetic epistasis experiments in both, MFRN1-high and MFRN1-low liver cancer cell lines by cell competition assays (Fig. 2c). Here, SLC25A28 is linked to liver cancer.