S 100

Tissues, cells, and exosomes lysates were prepared in RIPA buffer (KeyGEN BioTECH) and quantified using Bradford Protein Assay (KeyGEN BioTECH). Subsequently, the lysates were subjected to SDS–PAGE, transferred onto PVDF membranes (Millipore). Then membranes were incubated with primary antibodies overnight at 4 °C. The following primary antibodies were used: fibronectin (Santa Cruz, sc-69681, 1:200 dilution), S100 (Santa Cruz, sc-53438, 1:200 dilution), KLF2 (Abcam, ab203591, 1:500 dilution), KLF4 (Abcam, ab106629, 1:1000 dilution) and Claudin5 (Abcam, ab15106, 1:1000 dilution), TSG101 (Abcam, ab125011, 1:1000 dilution), CD63 (Abcam, ab59479, 1:1000 dilution), β-actin (Proteintech, 20536-1-AP, 1:2000 dilution), ZO-1 (Cell Signaling, #8193, 1:1000 dilution), occludin (Abcam, ab216327, 1:1000 dilution), VEGFR2 (Cell Signaling, #9698, 1:200 dilution), ERK (Cell Signaling, #4695, 1:1000 dilution), p-ERK (Cell Signaling, #4370, 1:1000 dilution), AKT (Cell Signaling, #4691, 1:1000 dilution), p-AKT (Cell Signaling, #13038, 1:1000 dilution). Following incubation with the specific HRP-conjugated antibody (Fdbio science, FDM007 or FDR007, 1:10,000 dilution), chemiluminescence signal was detected using FDbio-Femto ECL western blotting detection reagents (Fdbio science, Hangzhou, China). Uncropped scans of the most important blots are shown in Supplementary Figures 10 and 11.