Western Blotting of Cellular and Exosomal Proteins

Western blotting was performed as previously described^{30 (link)}. Total protein from cells (10 μg) and exosomes (10 μg) was fractionated using an electrophoretic gradient across Mini-PROTEAN tris-glycine extended gels (BIO-RAD, Richmond, CA, USA). Measurement of protein concentration was performed using a Bradford Protein Assay Kit (Takara Bio), according to the manufacturer’s instructions. The gels were then transferred onto Immun-Blot PVDF membranes (BIO-RAD) under wet electrophoretic conditions. The blotted protein was blocked for 1 hr at room temperature with Odyssey blocking buffer in PBS (LI-COR, Lincoln, NE, USA) and was followed by incubation overnight at 4 °C with the following primary antibodies: 1:1000 anti-CD63 mouse monoclonal antibody (BD Biosciences, San Jose, CA, USA); 1:1000 anti-cytochrome-c mouse monoclonal antibody (BD Biosciences); 1:1000 anti-calnexin rabbit monoclonal antibody (Abcam) and 1:1000 hFAB Rhodamine (#12004168 - Bio-Rad). Primary antibodies were detected by IRDye 800CW anti-rabbit IgG and IRDye 680RD anti-mouse IgG secondary antibodies (LI-COR) and were incubated with the protein-blotted membrane for 1 hr at room temperature. Fluorescence was then detected on the Odyssey imaging system (LI-COR).