TABLE 2.

Tumor induction by virus with S257C mutation^a

Characteristic	PTA with S257C mutation	PTA
No. of mice with tumors/total no. of mice	48/48	256/259
Mean age (days) at necropsy (range)	83 (53–227)	108 (43–381)
No. of epithelial tumors (%)
Hair follicle	40 (83)	229 (88)
Thymus	33 (69)	227 (88)
Mammary gland	23 (48)	126 (49)
Salivary gland	0 (0)	148 (57)
No. of mesenchymal tumors (%)
Kidney	17 (35)	123 (47)
Bone	12 (25)	58 (22)
Subcutaneous connective tissue	2 (4)	56 (22)

^aTumor profiles were carried out as previously described (27); data for the wild-type strain were previously reported (27).