Figure 1. Chimeric mice are composed of varying degrees of wild type and Arf ^−/− cells. A-C: Representative photos of 10-week-old mice that have low (A), medium (B) and high (C) amounts of Arf ^−/− cells based on coat color. D and E: Representative photograph of ethidium bromide-stained gel of PCR amplification of wild type (WT) and targeted (KO) Arf alleles from tail-derived DNA (D) and their quantification (E). Black and white bars represent Arf ^−/− and wild type genotype, respectively. Arf ^+/− and Arf ^−/− are included as controls. Letters designating individual animals are consistent throughout the manuscript.