Time-lapse confocal imaging of calcein-labeled 4T1 spheroids before and after photobleaching of cells and multicellular regions within invasive strands in the absence (control media) and presence of the gap junction inhibitor (CBX) in 3D collagen I. Field size: 213 × 122 µm. The playback speed is indicated in the time stamp of the video. Related to Figs. 2 b and S2 c.