Table 1.

Quantification of MT plus end dynamic behavior in contacted and noncontacted edges of newt lung epithelial cells

Parameter	Fully contacted cells, +MT enda (n = 45 MTs, 8 cells)	Contacted sides of migrating cellsa			Leading edge of migrating cells, +MT end perpendicularb (n = 22 MTs, 13 cells)	Leading edge of migrating cells, +MT end parallelb (n = 22 MTs, 13 cells)
		Dynamic & Quiescent Combined (n = 39 MTs, 5 cells)	Dynamic MTs (n = 18 MTs, 3 cells)	Quiescent MTs (n = 21 MTs, 5 cells)
% Time in Growth/Shortening/Pause	7.1/5.5/87.4	14.5/11.7/73.7	46.2/38.7/15.05	3.4/4.7/94.8	35.7/24.2/40.1	75.6/17.7/6.7
Growth rate (μm/min)	4.3 ± 3.6	9.1 ± 5.1	8.9 ± 4.4	10.5 ± 8.7	4.5 ± 2.7	6.8 ± 3.9
Growth duration (min)	0.5 ± 0.3	0.4 ± 0.2	0.4 ± 0.2	0.4 ± 0.3	0.6 ± 0.4	0.9 ± 0.7
Shortening rate (μm/min)	3.7 ± 2.4	8.0 ± 5.0	8.5 ± 5.0	6.3 ± 4.7	5.2 ± 4.3	7.6 ± 5.4
Shortening duration (μm/min)	0.5 ± 0.3	0.4 ± 0.2	0.4 ± 0.2	0.3 ± 0.1	0.5 ± 0.5	0.4 ± 0.2
Catastrophe frequency (min−1)	1.30	1.65	1.43	1.12	1.57	0.61
Rescue frequency (min−1)	1.90	1.80	1.48	1.34	2.31	2.59
Dynamicity (dimers/s)	15.3 ± 29.5	125.4 ± 142.1c	253.1 ± 113.1c	13.4 ± 29.2	63.9 ± 33.0c	171.5 ± 79.3c

Values are means ± SD. 

^a No qualitative differences between the dynamic behavior for MTs of different orientations with respect to the cell edge were noted. 

^b Data taken from Waterman-Storer and Salmon (1997). For comparison of assembly dynamics of parallel and perpendicular MTs in migrating cells, 22 MTs that grew from 0 to 30° from perpendicular to the cell's edge and then underwent a bend and grew from 0–30° from parallel to the cell edge and were followed. Assembly parameters were determined for the periods during which the MT was within these angular ranges. The period when the MT was bending was discounted in the averages. 

^c A statistically significant difference from fully contacted cells (p < 0.01).