Table 1.

Tumor incidence in Fhit^−/− and DKO mice

Genotype	Treatment (weeks)		number of tumors				Tumor bearing mice	Total mice	Tumors/ mouse
			≤0.5mm	~1mm	≥2mm	Total
Fhit−/−		15	0	0	0	0	0(0)	2	0
	NMBA,	15	5	2	0	7	3(75)	4	1,75+1.3
		25	0	0	0	0	0(0)	12	0
	NMBA,	25	43	21	7	71	22(95.7)	23	3.09±2.37
Fhit−/−Nit1−/−(DKO)		15	1	0	0	1	1(25)	4	0.25±0.5
	NMBA,	15	10	3	0	13	6(100)	6	2.25±0.96
		25	0	5	1	6	3(18.8)	16	0.313±0.7
	NMBA,	25	65	74	28	167	31(96.9)	32	5.03+3.02

Upon dissection, esophagus, stomach, liver, kidney, spleen and intestine were examined and tumors were only found in esophagus and forestomach. Tumors were measured and enumerated by visual inspection. Numbers in parentheses denote percentages of tumor bearing mice. Tumors per mouse was expressed as means and standard deviation and pairs of the mean values were compared by Student t-test for: Fhit−/− vs NMBA-treated Fhit−/− 25 week (P<0.001); DKO untreated vs DKO treated 25 week (P<0.001); untreated groups (P<0.10) and 25 week treated groups (P<0.01).