BLOC-2-mediated cargo delivery to maturing Weibel-Palade bodies. Immature Weibel-Palade bodies are generated in an AP-1/clathrin-dependent pathway by packaging of VWF quanta (black capsules), CD62P, and other cargo in the trans-Golgi network. Immature WPBs acquire CD63 in an AP-3-dependent pathway from endosomes. The findings of Sharda et al show that complex-formation between BLOC-2 and the exocyst is needed for transporting CD63 to immature WPBs (dashed red box 1). Fully mature WPBs are tethered to the plasma membrane through the exocyst complex (dashed red box 2). Sharda et al propose that the exocyst acts as a “clamp” preventing premature release of WPBs. Fusion of WPBs is mediated by so-called SNARE complexes. Recent findings have shown that SNARE proteins such as VAMP8 are recruited onto maturing WPBs through the same BLOC-2/AP-3-dependent pathway that is used by CD63.