<p>Lymphomas (shown as large orange sphere) were grown <i>in vivo</i> by tail vein injection of either drug-sensitive <i>Eμ-myc/Arf-/-</i> or drug-resistant <i>Eμ-myc/p53-/-</i> lymphoma cells. The inguinal lymph node tumor was excised, fixed, and sliced for histology sections (5 µm apart) every 100 µm along the tumor. A total of five sets (S1 through S5) of histology sections were obtained (for simplicity, the figure only shows three sets). The sections in each set were stained for cell viability (H&E), hypoxia (HIF-1α), proliferation (Ki-67), apoptosis (Caspase-3), and vascularization (CD-31).</p
