Human laminin 511

Reporter cells were mixed with unlabeled parental cells at 1:9 ratio and plated at a total density of 20,000 cells/cm² on glass-bottom plates (MatTek) coated with human laminin-511 (BioLamina) >12 hr before imaging. Images were acquired every 15 min for ∼50 hr with daily medium change. Cells were segmented and tracked from the acquired images using our own Matlab code (see Supplemental Information for image analysis methods).

The culture plates or cover slips were coated with 10 μg/ml mouse laminin (Invitrogen) or 10 μg/ml and 1 μg/ml human laminin 511 (BioLamina) in PBS over night at 4 °C. After laminin coating, the remaining uncoated surfaces were blocked with BSA for 1 hour at 37 °C. The culture plates and cover slips were washes 3 times with PBS before use.
Cells were harvested by Accutase (Millipore). Serum-containing DMEM was used to inactivate Accutase. Cells were then washed with serum free DMEM, counted and allowed to recover in suspension for half an hour at 37 °C. For cell attachment assay, cells (3 × 10⁴ cells per well) were seeded onto the laminin coated 96-well plates and incubated for 4 hours. After removing the non-attached cells, the attached cells were fixed with 96% ethanol for 10 minutes and stained with crystal violet (0.1% in water) for 20 minutes. After extensive washing, the stained protein was solubilized with 0.5% SDS and the absorbance was measured at 600 nm.