Figure 3 Munc13–4 protein expression is greatly reduced or absent in many cells. Western blot of natural killer cells (left and right) or CD8+CTL (middle panels) lysates from healthy donors (controls 1–3) and patients as indicated, probed with anti‐Munc 13–4 and re‐probed with anti‐actin. Molecular weight markers (kD) are shown on the left.