Figure 4.

Intrachromosomal recombination induced in mouse FL-10 cells following transfection with the indicated vectors. The cells were transfected with the plasmid vectors by co-mixture with cationic lipids. One day later, the cells were placed in HAT-containing medium to select for TK+ recombinants, and surviving colonies were enumerated 10 days later. The results are presented as the frequency of HAT-resistant cells per 10⁶ cells transfected. The mean values from at least three independent experiments are presented [except for A + B(rev), for which data from two experiments are shown]. The standard error is indicated by the error bars, and the compiled colony counts are listed above each bar. A, B, B(AG30) and B(rev) indicate the vectors pssXA, pssXB, pssXB(AG30) and pssXB(rev), respectively.