Neoplastic transformation and invasion of isografts of Comma/PDK1 cells. H&E stained paraffin-embedded tissue obtained from isografts of cells transduced with either empty virus (Ctl) or PDK1 (T1, T2, T3) 8 weeks after transplantation. Mammary isografts of control cells have normal lobuloalveolar ductal morphology with surrounding adipose tissue. Comma/PDK1 isografts produced poorly differentiated adenocarcinomas with solid cords of cells with little gland formation (T1), invasion of underlying skeletal muscle (T2) and vascularity (T3). Magnification: 100×.