Fig. 1
SKBR3-pool2 cells as compared to the parental SBKR3 cells grew tumors in nude mice with a significantly faster rate and retained trastuzumab resistance phenotype in vivo. A SKBR3 or SKBR3-pool2 cells (5 × 106) were injected s.c into the flanks of 5-week-old female nude mice (n = 8/group). Mice were observed three times and tumor formation was measured twice a week. Tumor volume was calculated and expressed as cubic millimeters (mean ± SD). B When tumor volumes reached ~ 80mm3, the mice bearing tumors-derived from SKBR3-pool2 cells were treated with either control (PBS) or trastuzumab (20 mg/kg) twice a week for seven times (n = 5/group). Tumor volume was expressed as cubic millimeters (mean ± SD). Treatment with trastuzumab had no significant effect on SKBR3-pool2 tumor growth at all-time points examined. Statistical analyses were performed with two-sided student’s t tests