FIGURE 5.

Reversibility of the effects of the PI3Kδ-selective inhibitor GS-9820 on osteoclast retraction. Rat osteoclasts were imaged by time-lapse phase-contrast microscopy and exposed to vehicle or GS-9820 (1 μm) from 0 to 30 min, as indicated by the horizontal bar above the data in B. A illustrates 2 different osteoclasts, each shown at 3 times. i, lamellipodia remain well spread in vehicle-treated osteoclast. ii, GS-9820 induces retraction of lamellipodia (evident at 15 min). Following washout of GS-9820 at 30 min, lamellipodia respread (evident at 40 min). B, planar area of osteoclasts was calculated periodically and expressed as a percentage of the mean initial area before time 0 (from −10 to 0 min). Data are mean ± S.E. There was no marked change in osteoclast area in vehicle-treated cells (n = 3 independent preparations, a total of 8 osteoclasts). In contrast, the planar area exhibited a significant decrease in the presence of GS-9820 and returned promptly to control values following its washout (n = 3 independent preparations, a total of 5 osteoclasts). Differences were assessed using a two-way ANOVA and Bonferroni's multiple comparisons test. * indicates p < 0.05 compared with vehicle at the corresponding times.