Tumorigeneicity and inactivation of p53 in arsenic-transformed BEAS-2B cells. BEAS-2B cells were chronically exposed to 0.1 μM arsenic for 24 weeks. A, Cell transformation assay. Chronically arsenic-exposed BEAS-2B cells and their passage-matched parent cells were used to examine cell transformation. B, C, and D, The transformed cells from single colony were picked and continued to grow. Arsenic-transformed cells (BEAS-2B-As) and passage-matched non-transformed ones (BEAS-2B) were prepared for tumorigenecity assay (B), luciferase assay (C), RT-PCR (D), and immunoblotting (E). *, p<0.05 compared to passage-matched parent BEAS-2B cells.