The centrosome was laser-ablated in immortalized human pigment epithelial cells (hTert-RPE1) that stably express centrin1-GFP (; ). GFP signal is shown in green in all panels. A, E: Cells prior to ablation with the intact centrosomes (arrows). B, C: Success of the ablation was confirmed by collecting an image stack at a significant time after the operation. Arrows in B and F indicate the lack of centrosomes at the location indicated in A and E, respectively. C: The cell shown in A and B was fixed and immunostained for tubulin (red) and the Golgi marker G97 (cyan). D: A bystander cell in the same preparation as C with an intact centrosome (arrow). G: The cell shown in E and F was incubated on ice for 40 minutes resulting in complete MT depolymerization (), allowed to recover at room temperature for 5 minutes to initiate MT re-growth, and then fixed and immunostained for tubulin (red) and the Golgi marker GM130 (cyan). H: A bystander cell in the same preparation as G with an intact centrosome (arrow). White outlines show cell borders in G and H. I, J: The central regions of the cells shown in G, H, respectively. Yellow chevrons indicate Golgi-derived MTs. White arrow indicates the centrosome.

A, MT seeds nucleated at the cis-Golgi by an AKAP-dependent protein complex (possibly including PTTG1/securin and γ-TuRC) might relocate to the TGN where they are stabilized by CLASPs and elongate. B, Molecules located at the sides of both cis-Golgi cisternae and the TGN act in concert for nucleation and stabilization of MTs. C, MTs that are nucleated by an AKAP-dependent complex at the cis-Golgi regions distant from the TGN are unstable in the absence of CLASP-stabilization.

Golgi-derived MTs drive the correct assembly of polarized Golgi complex at the cell center, which is essential for directional post-Golgi trafficking toward the front of a motile cell; this is, in turn, critical for cell polarity and polarized cell migration.