Increased senescence and apoptosis in tumor cells treated by T-oligo and IR. Mammary tumor cells isolated from MMT mice were treated with 40 μM T-oligo, Control-oligo or medium (diluent) alone for 24 hours and then irradiated. Cells cultured in medium alone were used as control. The tumor cells were collected 24 hours after 3 Gy IR and assayed for senescence and apoptosis. (a, b) β-gal staining. (a) The cells stained blue are β-gal positive cells (magnification 60×). (b) Percentage of β-gal positive cells in T-oligo or control-oligo-treated dishes with or without IR is presented in a bar graph. (c, d) TUNEL staining. (c) The cells stained in brown color are apoptotic cells (magnification 60×). (d) Percentage of apoptotic positive cells in T-oligo or control-oligo-treated tumor cells with or without IR is presented in a bar graph. Statistical significance from repeated experiments was determined by X2-test.