The pflare-exon 18 screens of the MGC cDNA expression library. The pflareG-exon 18 screen (blue) and the pflareA-exon 18 screen (yellow) identified 28 common activator clones (A) and 21 common repressor clones (B) from the MGC cDNA library. The two screens also identified 124 overlapping spiked-in PTBP1 clones (B). The identified genes are enriched for genes involved in RNA splicing (C) and RNA binding (D) compared to the whole MGC gene set. (E) RT-PCR validated changes in pflareG-exon18 mRNA splicing after transient transfection of the identified genes. Note that both human and mouse genes were recovered in the screen. Following nomenclatural rules, genes are in italic font with human genes in all capital letters. (F) A plot of the M values in the pflareG-exon 18 screen versus the ΔPSI measured by RT-PCR. Each dot represents one of the 34 tested genes.