Integrin-Ligand Interactions Control Migration Figure 2. CHO.B2 cells expressing different integrins show differences in protrusion and adhesion. (A) CHO B2 cells were co-transfected with paxillin-mCherry and a5-GFP, a6-GFP or aL-GFP + b2-GFP and then plated on FN, LN or ICAM-1. In the merged color panels, paxillin is in magenta and integrins are in green. Scale Bar = 10 mm. (B) Kymographs of cell edge and adhesions in protrusions. The retrograde fluxing of the integrins and paxillin on LN or ICAM-1 are revealed by the movement of discrete molecular units within the adhesion; this is apparent in the downward parallel line formed in the kymographs that overlie adhesions: paxillin (left), integrin (center) and merged (right). Note that the entire adhesion remains largely in place during the fluxing on LN; this also occurs on ICAM-1. doi:10.1371/journal.pone.0040202.g002 contrast, RLC phosphorylation was low and largely substrate concentration-independent in aLb2-expressing CHO.B2 on ICAM-1. CHO.B2 cells expressing a5-, a6- or aL-+b2-GFP migrating on fibronectin, laminin, or ICAM-1, respectively, showed no significant difference in the relative expression of MHC IIA, MHC IIB, or RLC (Figure 3A). Taken together, these data do not reveal a tight correlation between substrate/integrin utilization, migration and RLC phosphorylation for all integrins tested. To investigate further whether the differences observed in adhesion and migration were due to the differential activation or other effect of myosin II on cells expressing the different integrin/ PLoS ONE | www.plosone.org 5 July 2012 | Volume 7 | Issue 7 | e40202