Table 1. Comparison of clonogenic cell survival of four colon cancer cell lines with initial DNA damage and initial DNA repair rate assessed using the comet assay.

	Clonogenic assay	Comet assay (initial damage)a	Comet assay (damage rejoining)b
Cell Line	SF2±1 s.e.m.c	Tail moment U Gy−1±1 s.e.m.	d[r2]	Initial (0–15 min) repair half time after 5 Gy (min)	[r2]d
HT29	0.72±0.29	2.02±0.13	0.992	13.7	0.83
SW480	0.69±0.32	2.20±0.08	0.997	10.7	0.79
SW707	0.50±0.19	2.64±0.13	0.993	12.2	0.90
SW48	0.14±0.18	3.99±0.10	0.999	13.7	0.87

^aInitial damage per unit dose expressed as the linearly fitted slope of the four observations (0–5 Gy) for each dose–response curve from Figure 3.

^bRate of damage rejoining expressed as the slope of the exponential fit to the first three observations (0–15 min) for each curve from Figure 4.

^cFraction of cells surviving exposure to 2 Gy.

^dCorrelation coefficient of fit.