Fig. 2. Colocalization of rearward traction stress spots and F-actin accumulation sites, and close contact of the cell surface to the substratum in wild-type cells. (A) Simultaneous recording of fluorescence of GFP-ABD120k (left) and traction stresses (right) of a migrating wild-type cell transformed with GFP-ABD120k under confocal microscopy. Stress spots (a'-c') appeared at locations where F-actin accumulated (a-c) in the anterior and middle regions of the cell. The typical sequential stress map shown was made from three migrating cells randomly selected from 11 cells. (B) Simultaneous recording of fluorescence of GFP-ABD120k (left) and IRM imaging (right) of a migrating wild-type cell transformed with a GFP-ABD120k construct under confocal microscopy. Dark spots surrounded by white rings (d'-g') appeared at locations where F-actin accumulated (d-g). The white ring surrounding a dark spot is a feature of focal contacts in Dictyostelium (Uchida and Yumura, 2004). The time-courses are indicated for each picture of GFP-ABD120k. Yellow arrows at 0 seconds in panels A and B indicate the direction of cell migration. Bars, 4 µm.