Table 1.

Recovery of spontaneous recombination events

Experiment numbera	RTXb	Total no. coloniesc	Colony frequencyd (10−7)	Recombination frequencye (10−7)
1	−	10	1.6	1.5
	+	32	5.2	4.7
2	−	12	3.3	2.7
	+	34	17.4	13.6
3	−	7	1.7	1.2
	+	24	10.9	10.1

^aThree independent experiments, each involving10 independent subclones of cell line pLB4/11, were conducted in order to measure recombination frequency.

^bPortions of cells from each subclone in each experiment were untreated (−) or treated (+) for 24 hours with 1.5 nM RTX prior to plating into G418 selection as described in Materials and Methods.

^cTotal number of G418^R colonies recovered from all subclones for a given experiment and condition.

^dCalculated by dividing the total number of G418^R colonies by the total number of viable cells plated into G418 selection.

^eCalculated by multiplying colony frequency by the percentage of colonies that arose from bona fide recombination events as assessed by PCR and AluI restriction analysis as described in text.