Figure 8.

Phosphorylation of LKB1 at Ser334 attenuates its tumor-suppressive activity in nude mice transplanted with human MDA-MB-231 breast cancer cells. Same numbers (5 × 10⁵) of stably transfected MDA-MB-231 cells were implanted into the mammary fat pads of female nude mice. (A). Tumor onset day was recorded as the first day of the palpable tumor formation. (B). Tumor growth was monitored weekly by measuring the tumor sizes and calculated as tumor volume as described in Methods. (C). At eight weeks after implantation, mice were sacrificed for tissue collection. Representative tumor development images were shown in left panel and the wet weights of tumors measured and recorded in the right panel. (D). Representative microscopic images of PCNA-stained tumor sections from the four groups of mice. Positive-stained cells were manually counted and calculated as percentage against total cells. Scale bar = 200 μm. The results are exhibited as the means ± SEM. * P < 0.05 and ** P < 0.01 vs pcDNA groups; # P < 0.05 vs WT groups (unpaired t test, n = 6).