Fig. 6. PTP1B DA puncta develop from ER tubules extending over cell-matrix adhesion foci. PTP1B null cells were co-transfected with GFP-PTP1B DA and mRFP-paxillin, and 24 hours later were replated for 30 minutes on fibronectin-coated coverslips. Cells were immediately analyzed by time-lapse confocal microscopy. Different regions of a cell in selected frames of a time-lapse sequence are shown (A-C). Numbers over the time-lapse series indicate minutes elapsed. Arrows indicate punctate structures that develop from ER tubules at the tips of new paxillin foci. Yellow arrows in B indicate a punctate structure that forms and disappears, whereas the paxillin foci remain. Note that the punctate structures become larger after the arrival of additional ER tubules (arrowheads, 120 minutes in A; 26 minutes in B; 114 minutes in C). Bar, 10 µm. See also Movie 1 in supplementary material.