Figure 7: Comparing the viability of clustered tumor cells (Cl-TC) and single tumor cells (Sl-TC) to doxorubicin.

(a) Images showing the viability of tumor cells in clusters of different sizes when exposed to 10 μM dox. Each image is a composite rendition showing live (green) and dead (red) cells. (b) The viability of two batches of MCF-7 cells were measured over time when exposed to 10 μM doxorubicin. Batch [A] contained only single tumor cells (Sl-TC^A, n = 2275 and Batch [B] contained a mixed population of single tumor cells (Sl-TC^B, n = 1054) and clustered tumor cells (Cl-TC^B, n = 1621 cells out of 620 clusters). To test whether the clustered cells showed different response to drug compared to single cells, we performed standard unpaired t- test with 95% confidence interval at 10, 20 and 24 hrs. Statistical significance (p value) is represented with asterisks (*) with the following convention - *P < 0.05, **P < 0.01, ***P < 0.001. For all time points, cells in clusters (Cl-TC^B) showed statistically higher viability than the viability of single individual cells [(Sl-TC^A) and (Sl-TC^B].