Table I.

Morphometric analysis of cell extensions in 3D collagen matrices

Cell sample	Growth factor	Projected cell area	Branch length	Number of branches
		μm2	μm
Mock	none	1,583 ± 422	57 ± 20	9.8 ± 3.3
siRNA	none	941 ± 359	45 ± 19	6.3 ± 2.5
	P value	0.048	0.043	0.14
Mock	PDGF	2,547 ± 773	74 ± 23	12.7 ± 3.4
siRNA	PDGF	1,006 ± 279	44 ± 15	8.0 ± 2.5
	P value	0.003	0.0003	0.03

PAK1-silenced and mock-transfected cells were harvested and used to prepare floating collagen matrices. Samples were incubated for 4 h in DME containing 5 mg/ml BSA and 50 ng/ml PDGF, as indicated. At the end of the incubations, samples were fixed and stained with rhodamine-phalloidin for actin. For each value, measurements were made on 50 cells that were photographed at random.