Characterizing the initial stages of oncogenic transformation in bladder cancer. Littermate male mice were transferred in single-use plastic cages in order to be treated with the BBN carcinogen. The treatment dose used in this work was 0.05% BBN delivered in drinking water for up to 12 days. Bladder samples were collected at day 1, 4, 8 and 12 from treated mice along with the age-matched controls (non-treated). The drinking water was changed every fourth day. The weights of the mice and BBN water intake were measured every four days and mice were checked regularly for any signs of discomfort and pain.