Plasmids encoding a signal guide RNA are designed to knock-in a H2B-GFP-pA reporter cassette and a loxP site flanked PGK-NEO cassette into exon 2, the endogenous translational start site of the gene. Cre-mediated recombination removed the floxed neo cassette. Quantitative RT-PCR confirmed that 3' UTR was not amplified although both spliced and unspliced 5'UTR is detected. This is a null allele and a reporter allele. (J:243623)