Figure 1.

Western blot detection of hnRNP A2B1 and hnRNP Q in HMEEC secretions. Proteins (50 μg) were loaded in an SDS-PAGE and separated. The positive control consisted of 50 µg protein from a human exosomal protein suspension obtained commercially from System Biosciences. After electrophoresis, proteins were transferred to a nitrocellulose membrane, which was then exposed to antibodies anti-hnRNP A2B1 (37 kDa) (A) and the normalized pixel count for 3 independent Western blots (data not all shown) over positive control (B), or anti-hnRNP Q (70 kDa) (C). Note that the protein doublet for hnRNP A2B1 is present as a result of the proteins’ 2 isoforms (hnRNPB1 is 353 aa, 37.4 kDa; hnRNPA2 is 341 aa, 36 kDa). Multiple bands for hnRNP Q likely represent protein fragmentation.