Oncogenicity of murine mammary tumor virus produced in tissue culture: brief communication.

Murine mammary tumor virus (MuMTV), produced from a glucocorticoid-stimulated C3H mouse mammary adenocarcinoma cell line, was free of murine leukemia virus and oncogenic for weanling BALB/c mice. Adenocarcinomas were induced by MuMTV as early as 136 days post inoculation and with as low as 5 X 10(3) virus particles/mouse. Tumor incidence did not correlate directly with virus dose; rather, it was low at higher MuMTV concentrations (1.2 X 10(8) particles/mouse), reached and optimum at 1.3 X 10(5) particles/mouse, and decreased with virus dilution.