We observed that the average WPB length in KLF2- transduced cells is consistently reduced by 0.4 mm when compared to mock-tranduced cells. Biogenesis and elongation of WPBs is mediated by a clathrin/AP-1 coat that transiently associates with newly forming WPB in the TGN. We speculate that expression of KLF2 modulates the function or expression of these proteins thereby limiting the elongation of newly forming WPBs. The overall multimeric composition of secreted VWF in medium of KLF2- and mock-transfected BOECs was similar, suggesting that the observed decrease in WPB length is not due to a change in multimerization of VWF.. However, our analysis did not allow us to assess whether the maximum size of VWF multimers is affected by the expression of KLF2. Upon stimulation of endothelial cells with cAMP-raising agonists a significant number of WPBs escape from their release and are transported to the MTOC. Here, we show that clustering of WPBs at the MTOC is impaired in KLF2 expressing endothelial cells. Clustering of WPBs is dependent on dynein-mediated transport along microtubules. When laminar fluid shear stress is applied microtubules align in the direction of the flow and the MTOC migrates downstream of the nucleus. Expression of KLF2 does not result in major changes in the properties of microtubules nevertheless clustering of WPBs is impaired in these cells. Despite the absence of clustering at the MTOC a considerable number of WPBs is retained inside the KLF2 expressing cells that have been triggered by cAMP-raising agonists. We speculate that defects in minus end directed transport of WPBs along microtubules prevent perinuclear transport under these conditions. It has been found previously that the retrograde transport of WPBs is mediated by the dyneindynactin complex and that protein kinase A is involved in this process, as inhibition of PKA prevents clustering of WPBs at the MTOC. It is unlikely that KLF2 targets activation of PKA as it has been described previously that the sensitivity of KLF2 expressing endothelial cells for cAMP-raising agonists like Fulvestrant epinephrine and forskolin is not reduced. We speculate that KLF2 modulates PKA-mediated phosphorylation of motor protein complexes regulating retrograde transport of WPBs. We previously proposed that clustering of WPBs at the MTOC might be a mechanism to secure vascular homeostasis by preventing release of pro-inflammatory contents from WPBs. Previously, it was reported that the storage of Ang2 and Pselectin in WPBs was mutually exclusive. In this study, we have shown that Ang2 and P-selectin co-localize in WPBs. Pselectin is able to bind to the D’D3 domain of VWF via its luminal domain, however it was also reported that a targeting motif in the cytoplasmic domain of P-selectin was sufficient for sorting of P-selectin to WPBs. This makes mutual exclusion by competitive binding of P-selectin and Ang2 to VWF unlikely. KLF2 is known to cause downregulation of expression of proinflammatory cytokines, some of which can be present in the WPBs.