Elevated levels of cell-cycle inhibitors in LckCre-Myc^fl/fl thymocytes. (A) Semiquantitative RT-PCR with 5-fold serial dilutions for cell-cycle-related genes performed on c-DNA obtained from FACS-sorted DN3 and DN4 thymocytes. Data sets are representative of observations obtained in 3 independent experiments. (B) Quantitative RT-PCR analyses using RNA prepared from similarly sorted cells were performed in triplicate for the indicated genes. □ represents results for LckCre control; ▪ represents results for LckCre Myc^fl/fl mice. Error bars indicate SD. (C) Western blot of sorted cells (2 × 10⁶ per lane) probed with antibodies detecting the indicated proteins. Data are representative of 3 independent experiments.