Phalloidin–Atto 647N (65906, Sigma-Aldrich, 1:400) and Alexa
Fluor® 488 Phalloidin (A12379, Life Technologies, 1:100) were used to
stain filamentous actin. AlexaFluor-conjugated secondary antibodies (488, 555,
633, 647-conjugated anti-mouse, rabbit, goat, chicken and rat antibodies, Life
Technologies) were used in immunofluorescence (1:300 or 1:1000 (anti-chicken))
and FACS (1:200). The 4′6-diamidino-2-phenylindole (DAPI, Life
Technologies 1:10000) or DAPI-containing mounting medium (ProLong Diamond
Antifade Mountant with DAPI, Thermo Fisher) were used for nuclear staining. The
bovine plasma fibronectin (341631) was obtained from Merck. The collagen from
calf skin (C8919), poly-L-Ornithine solution (P4957) and laminin (L2020) were obtained
from Sigma-Aldrich. The laminin-521 was obtained from BioLamina. Rap1 inhibitor,
G5169-GGTI 298 trifluoroacetate salt hydrate (Sigma-Aldrich), was dissolved in
sterile DMSO.