Glass coverslips were prepared essentially as described previously (Mueller et al., 1992 (link)). In brief, they were coated with Oregon green® 488-conjugated gelatin (0.2 mg/ml in 2% sucrose buffer), cross-linked 15 min in 0.5% glutaraldehyde in PBS, and incubated for 3 min with 5 mg/ ml NaBH4 in PBS. After quenching with DME at 37°C, cells were plated on coated coverslips in DME containing 10% FCS with or without inhibitors and incubated at 37°C for 3 or 4 h before processing for immunostaining. Results were quantified by counting cells degrading matrix, as defined by ability to form at least one degradation patch regardless of its size, and represented as a percentage of the total (50 cells per treatment in at least two independent experiments).