Number of dead cells within the cohesive core of MCTS under drug treatment after transfer to new wells.

<p><b>(A)</b> Typical fluorescence images at 48h of living cells in green (calcein +) and dead cells in red (PI+) in control SW480 MCTS or in presence of 5-FU (300 μM). <b>(B)</b> Quantification of PI+ dead cells per unit volume for each cell line as a function of the 5-FU concentration. Error bar = SEM (standard error of the mean), (n = 12 for each cell line). Scale bar: 200 μm.