Cell Culture.

RPTPα^+/+ MEF cell line was a gift from Dr. Sap Jan, New York University School of Medicine. MDA-MB-231 cell line was obtained from the American Type Culture Collection. MEF, MEF-Src (MEF expressing the constitutively activated Src-Y530F mutant), and MDA-MB-231 cell lines were grown in Dulbecco’s Modified Eagle Medium (DMEM) supplemented with 10% FBS (vol/vol), 100 unit/mL penicillin, and 100 μg/mL streptomycin (Thermo Fisher Scientific) in a 37 °C incubator with 5% CO₂. Unless otherwise stated, MEF-Src cells and the substrate coated with fibronectin (Thermo Fisher Scientific, 33016015) were used in the experiment.