Figure 3. The maintenance of self-renewal in ObR+ cells. (A) Percentage of sorted ObR+ and ObR− cells after culturing for various times as analyzed by flow cytometry. (B) Leptin stimulated tumor development by implanted U87R cells. nude mice implanted with U87R (4 × 104) cells were randomly assigned and received i.p. injections of either PBS or leptin (2 μg/g body weight) every other day for 2 wk.