Figure 2

Transformation of cells selected for the ability to replicate under chronic exposure to ICR191. A. Loss of contact inhibition by the MCF-10A cells selected for DNA damage-resistance. Passage- matched control MCF-10A cells (left) and the cells from the MCF-10A alpha culture after six months of cultivation in the presence of ICR191 (right) were plated in the medium without carcinogens and allowed to grow until the state of confluence. The 3D structures formed by DNA damage-resistant at the state of confluence cells are seen under a light microscope. B. Microscopically visualized colonies produced in three weeks in soft agar by the MCF10Aα cells selected for resistance to ICR191 (right) but not by the control passage-matched MCF-10A cells (left). C. A higher rate of MCF10Aε cell-replication after cultivation for four months in the presence of ICR191. Passage-matched control MCF-10A cells and the cells from the MCF10Aα and MCF10Aε cultures after four months of cultivation in the presence of ICR191 were seeded in 30 mm plates in triplicate (5 × 10⁴ cells per plate), and the cell numbers were counted at the indicated times using a hemocytometer. Standard errors were calculated on the basis of triplicate measurements.