Bioluminescence images were acquired after injection of EL-Arf−/− cells or control. a) Bioluminescence images are shown on day 7 and 14. The arrow designates the ILN, which is visible with bioluminescence by day 14. The arrowhead shows bone marrow (femur) and the red circleindicates spleen (N=10 each group). b) and c) EGFP+ cell analysis using FACS. b) Representative FACS dot plot of EGFP+ cells in BM, spleen, and ILN on day 7 and 14 after injection. c) The columns represent the means of percentages of EGFP+ cells from three independent experiments (N=8 each group). Bars, S.E.M. *p<0.05 d) Expression analysis of EL-Arf−/− lymphoma cells in mouse inguinal lymph node using highly-sensitive PCR on day 3. The upper panel shows either Arf+/+ (endogenous normal cells) or EL-Arf−/− lymphoma cell expression pattern. The lower panel shows quantitative PCR. The indicated EL-Arf−/− cell number was exogenously added into the ILN directly, demonstrating that while we can detect as few as 100 EL-Arf−/− cells in the ILN, no lymphoma cells are detectable in an EL-Arf−/− injected mouse on day 3 (N=3, performed over three independent experiments).