Conditional gene-activation of integrated transposons. Colonies from the transfection of pTC-loxPTK-G with pKUb-SB11 (Fig 5C) were expanded in selective media containing puromycin. DNA from these transgenic colonies was isolated and analyzed by Southern hybridization. A) A schematic of pKT2C-loxPTK-G that shows the AseI restriction sites and the location of the PTK hybridization probe (diagonal lined rectangle) used for Southern analysis. B) A Southern blot of pKT2C-loxPTK-G colonies. The clones were analyzed without Cre excision, so integrants that result from transposition should be equal to or greater than the transposon size of 4.9 kb (open arrow). Whereas, bands associated with concatemer formation are found at 6.0 kb (vertical line arrow). The positions of the DNA marker bands of the 1 kb Quanti-Marker from ISC Bioexpress (Kaysville, Utah), are indicated by black dots on the right of each blot with sizes of 12, 10, 8, 6, 5, 4, 3, 2.5, and 2 kb shown. C) pKT2C-loxPTK-G colonies were transfected with pPGK-nlsCre and plated under gancyclovir selection. Clones with PTK eliminated by recombination became gancyclovir resistant and were counted. Cre-activation of all clones was determined to be significant (p < 0.5).