Table III. Effect of dominant-negative STAT5A and STAT5B expression on IL-3–mediated HEK293 IL-3R cell cycle progression.

	G0/G1	S	G2/M
	%	%	%
(HEK293 IL-3R + Neo   vector) FN	61 ± 2	31 ± 3	8 ± 2
(HEK293 IL-3R + Neo   vector) FN + IL-3	53 ± 3	38.5 ± 4	8.5 ± 2
(HEK293 IL-3R + Δ   STAT5A) FN	62.5 ± 3	30 ± 2	7.5 ± 1.5
(HEK293 IL-3R + Δ   STAT5A) FN + IL-3	63.3 ± 1	29.2 ± 2	8.5 ± 3
(HEK293 IL-3R + Δ   STAT5B) FN	60 ± 2	30.5 ± 2.5	9.5 ± 2
(HEK293 IL-3R + Δ   STAT5B) FN + IL-3	51.6 ± 1	39 ± 4	9.4 ± 2

HEK293 IL-3R cells, transiently transfected with the empty vector (Neo vector) or with dominant-negative STAT5A (ΔSTAT5A) or STAT5B (ΔSTAT5B) constructs, were serum starved for 24 h and let to adhere to FN-coated plates in the absence or presence of 20 ng/ml IL-3. After 18 h of stimulation, the cells were fixed with ethanol and DNA was stained with propidium iodide. The fluorescence related to DNA content was evaluated as described in Table II. The numbers are the mean ± SD of three different experiments done on separate days, each performed in triplicate.