Fig. 5. Effect of modulation of Src activity on podosome organization and dynamics. Temporal ratio imaging of GFP-actin, based on time-lapse microscopy of osteoclasts expressing GFP-actin (control); co-expressing GFP-actin and SrcY527F (SrcY527F); or co-expressing or GFP-actin and Src251 (Src251). Notice the elevated rate of podosome turnover and formation of ectopic podosomes in the SrcY527F-expressing cells, and the predominance of stationary podosomes in the Src251-expressing cells (0.5' and 10'). The calculated average podosome life span (± s.d.) is 52±25 seconds in SZL structures of SrcY527F cells, and 31±15 seconds in the ectopic podosomes of the same cells. The life span of the dynamic podosomes in Src251-expressing osteoclasts was 528±334 seconds. These data were based on measurements taken in five cells, with >200 podosomes for each cell type. Bar, 10 µm.