Actin recovery is independent of the presence of extracellular growth factors.

<p>A) Example of fluorescence recovery after FRAP under control conditions (10% FBS, FBS plot) and serum starvation for 16 hours (Starving plot). B) Summary data of the mean mobile fraction in MDA-MB-231 cells. The mean mobile fraction under FBS conditions was 62±5.2% (n = 6), as compared to 58±3% after 16 hours of starvation and 57±2% (n = 6) after PI3K inhibition with LY294002 (n = 6). It should be noted that we have included new control cells, growing in parallel and analyzed on the same day and under the same conditions; therefore, the average mobile fraction has a slightly different value that the overall mean average (70% versus 65%). C) The mobile fraction of non-cancerous cells under serum-starved conditions was reduced to 27±5.2% (n = 10) in mouse fibroblast and to 28±2.4% in MCF10A (n = 6), (p<0.05; Student's t-test). D) Recovery time summary graph. MDA-MB-231 growing in FBS tended to show faster dynamics (4.14±0.6 s) not statistically significant from that of starved cells (6.6±1.7 s). The use of LY294002, a chemical inhibitor of PI3K, did not affect recovery time (4.2±1.0 s). E) In contrast, serum starvation affected the recovery time of non-cancerous cells, increasing the time constant from 8.2±0.2 s to 9.5±0.1 s for MEFs (p<0.05) and 6.5±0.4 s to 8.0±1.2 s for MCF10A cells (p<0.05; Student's t-test).