Western blotting analysis of platelets from wild-type and Unc13d^Jinx mice. (A) Equal amounts of platelet extract from wild-type (WT) and Unc13d^Jinx mice (5 × 10⁷ platelet equivalents per lane) were separated using sodium dodecyl sulfate–polyacrylamide gel electrophoresis and analyzed by Western blotting using a polyclonal, anti-Munc13-4 antibody. The epitope used for antibody generation is indicated in the schematic diagram of mouse Munc13-4 in panel A. The position of the frameshift mutation is indicated (839 aa, ↑). (B) The platelet extracts used in panel A were probed with antibodies against the indicated SNARE proteins, secretion regulators, and cargo.