DC maturation and podosome loss.

Maturation of DCs during 24-hour culture with LPS results in almost complete loss of podosomes (panel A). In contrast with immature DCs, mature DCs are rounded cells that are adhere poorly on fibronectin and have little tendency to spread. IgG-injected mature DCs have the same morphology as uninjected cells, remaining unpolarized and unspread despite displaying active peripheral lamellipodial formation (arrowhead in panel B). Microinjection of V12Cdc42 (panel C) causes striking filopodial assembly (arrowheads in panel C) whereas V12Rac injection (panel D) stimulates vigorous ruffling (arrowhead in panel D) and lamellipodial formation (arrow in panel D). When V12Cdc42 and V12Rac are coinjected (panel E), both filopodia (arrowhead in panel E) and lamellipodia (arrow in panel E) are assembled.