TABLE 1.

Mutation counts

Mouse ID	TE	TA	No. mutations	No. cells	Treatment/control
1	69	220	0	2.07 × 108	Control
2	231	382	0	1.52 × 108	Control
3	82	233	0	1.60 × 108	Control
4	57	208	0	1.43 × 108	Control
5	204	355	1	1.80 × 108	Control
6	57	208	1	1.21 × 108	Control
7	82	233	2	1.74 × 108	Control
8	69	220	2	1.41 × 108	Control
9	284	435	2	1.58 × 108	Control
10	284	435	4	1.71 × 108	Control
11	158	188	0	1.16 × 108	Treatment
12	55	85	2	1.06 × 108	Treatment
13	55	85	0	1.02 × 108	Treatment
14	158	188	0	1.23 × 108	Treatment
15	71	163	2	1.25 × 108	Treatment
16	139	231	3	1.70 × 108	Treatment
17	101	193	7	1.53 × 108	Treatment
18	62	276	0	1.31 × 108	Treatment
19	71	285	2	1.39 × 108	Treatment
20	71	285	1	1.30 × 108	Treatment
21	96	310	12	1.61 × 108	Treatment
22	144	358	6	1.62 × 108	Treatment

Mutation counts were obtained by imaging the left caudal liver lobe of mice treated with a mutagen ENU (treatment) or the vehicle alone (control). T_E is the time of exposure (to ENU or vehicle) in days since birth, T_A is the time at which a mouse was imaged (in days since birth). The number of mutations (column 4) is the total number of mutant EGFP-expressing colonies observed and the number of cells (column 5) is the total number of liver cells scanned.