Fig. 5.

Generation and phenotype of the Cd4 minigene transgenic line. (A) Comparison of the CMV-GFP transgene and the Cd4 minigene. Regions unique to the Cd4 minigene are highlighted in red, including the Cd4 silencer (S), enhancer (E) and promoter (P). To further diversify the two transgene sequences and therefore to help isolate the role of the Col1a1 locus in transgene behavior, we inserted the cDNA encoding human CD4 upstream of GFP and replaced the β-globin poly(A) with an SV40 poly(A) sequence. The arrows indicate the PCR primers a/b and c/d used for screening ES cells for integration of the left and right ends of the flip-in vector, respectively. (B) PCR analysis of a correctly targeted ES clone using primers a/b and c/d. DNA from the parental KH2 ES cells was used as a wild-type control (WT).