Molecular and cellular analyses of p53ER^TAM lymphomas. (A) Analysis of tumor clonality through PCR amplification and detection of D-J junctions by Southern blotting. A, B, and C refer to 3 independent p53ER^TAM tumors. gDNAs from rodent fibroblasts and pro-B cells without D-J rearrangements were used as negative controls. gDNAs from total bone marrow and a previously characterized Myc-induced polyclonal lymphoma were used as positive controls. (B) Tumor volumes versus days of 4OHT treatment. Plots with squares and circles refer to Mp53ER^SEN and Mp53ER^RES tumors, respectively. Solid lines/filled symbols and dashed lines/open symbols refer to untreated and 4OHT-treated mice, respectively. Error bars represent SD. The inset depicts immunoblotting on Mp53ER^SEN and Mp53ER^RES cells, using anti-Arf and anti-Mdm2 antibodies. β-Actin was used as a loading control. (C, top) Histologic staining of representative specimens from panel B. Tissues were harvested 3 hours after the commencement of 4OHT treatment. (Middle) TUNEL staining of adjacent sections. (Bottom) Immunohistochemical staining for p53. Brown color refers to p53 expression, and blue color is counterstaining with hematoxylin. In the last 4 panels, insets represent tumors from untreated animals. Sections were analyzed using Axioskop 40 microscope (Carl Zeiss, Maple Grove, MN) equipped with a 20×/0.45 NA Achroplan objective lens and 10× eyepieces. Images were captured using Evolution QEi camera (MediaCybernetics, Houston, TX) and Phase 3 ImagePro software (Imaging Systems, Bridgewater, NJ) and further processed using Adobe Photoshop CS v8.0 (Adobe Systems, San Jose, CA).