Table 2. X-ray induced chromosomal aberrations in primary human fibroblasts irradiated in G2 phase of the cell cycle.

Cell line	X-ray dose (Gy)	Breaks/cell	Interchanges/cell	Total breaks/cell*	Induced breaks/cell**
VH10 (wt)	0	0.01	0	0.01	0
	0.1	0.10	0	0.10	0.09
	0.25	0.20	0	0.20	0.19
VU1174-F (RBS)	0	0.02	0	0.02	0
	0.1	0.10	0	0.10	0.08
	0.25	0.24	0	0.24	0.22

^*Frequency of total breaks estimated by counting one chromatid interchange as two breaks.

^**Induced break frequency is estimated by subtracting values obtained in control from those obtained after irradiating cells.