Southern blot analysis of Cre-mediated deletion of the stop element in induced kit^D814Vflox Mx1-Cre animals. Southern blot analysis of genomic DNA extracted from lymph node, liver, kidney, spleen, and bone marrow from kit^D814Vflox Mx1-Cre mice induced by intraperitoneal injections of pI:C. The Southern blot strategy based on a NotI (N) and BamHI (B) double digestion and an intron1–2-specific probe discriminates between the repressed transgene (flox Stop), kitD814V after Cre-mediated deletion of the stop cassette (del Stop), and the genomic wild-type kit allele (wt). Not drawn to scale.