Table 1.

Characteristics of 3T3 fibroblast cell lines

Genotype	Doubling time, h	% of cells in cell cycle phases			Saturation density, no. of cells per 3-cm dish	Cell size, mean FSC-H
		G1	S	G2/M
wt	43.5	41	39	19	1.1  × 106	482
p107−/−	41	41	40	18	4.9  × 106	318
p130−/−	45	40	39	22	1.8  × 106	420
p107−/−/p130−/−	41	30	62	6	4.5  × 106	354
pRB−/−	42	29	64	8	2.7  × 106	367
pRB−/−/p107−/−	41	35	59	5	3.8  × 106	389
pRB−/−/p130−/−	41	31	61	7	4.1  × 106	341

The doubling times were determined by plating 10⁶ cells in a 10-cm dish followed by cell counting 3 days later. The values shown are mean doubling times at passage 55–60. The saturation densities were measured by plating cells at 2 × 10⁵ in 3-cm dishes, followed by cell counting each day until saturation was reached. The relative size of asynchronously growing cells plated at 7 × 10⁵ per 10-cm dish 24 h prior to harvesting was measured by performing FACS analysis and plotting FSC-H histograms. The percentage of cells in the G₁, S, and G₂/M phases of the cell cycle in asynchronously growing populations plated at 8 × 10⁵ cells per 10-cm dish 24 h prior to analysis. The percentage of cells in each phase of the cell cycle (G₁, S, and G₂/M) was measured by BrdUrd incorporation (S phase) and two-dimensional FACS analysis. The data presented are a representative example of many experiments.