Figure 3.
Size Information of Spheres
(A) Average mammosphere size of MCF-7 and T47D cell lines. Red bar indicates mean size, and blue box indicates the 25th–75th quartiles. Whiskers represent the range of sizes, whereas red dots are outliers (for MCF-7: day 5, N = 3; days 7 and 14, N = 6. For T47D: N = 6 for days 7 and 14). Note that the y axis scale is different for T47D than MCF-7.
(B) Explanatory figure using size after 7 days compared with size on day 14 (N = 6, MCF7). Solid lines represent a sphere cutoff value of 50 μm. If this value is chosen the lavender box illustrates those individual clonal growths (termed Pre-spheres or PreSP) that were under 50 μm but grew to be spheres and were thus undercounted. The beige box illustrates those that were over 50 μm on day 7 but either died or shrunk by day 14 and were therefore overcounted.
(C and D) (C) Data from scatter charts were utilized to calculate the percent of misclassified spheres ([undercounted + overcounted]/total spheres). This was calculated for a range of cutoff values and plotted as a graph. Solid line is the weighted average, and the error is ±weighted SD. (D) The cutoff value with the smallest percent of misclassified data was calculated for each day using the graph in (C). For MCF-7 the results were 53 and 55 μm for days 5 and 7, respectively. For T47D the value was 35 μm.