Figure 1.

Lenalidomide induces actin polymerization in circulating monocytes from CLL patients throughout Rho and Ras family GTP-binding proteins. (A and B) Monocytes purified from peripheral blood mononuclear cells (PBMC) of 9 CLL patients were allowed to adhere and then treated with lenalidomide at the indicated concentrations or vehicle (DMSO) for 20 min. F-actin content was then inspected by rhodamine-phalloidin staining. (A) Two representative samples. (B) Quantification of cell staining, as mean value obtained from 5 different fields at 400X magnification normalized on control (100%, DMSO-treated monocytes). Lenalidomide induces actin polymerization in monocytes from CLL patients. Data represent 8 independent experiments. Columns and error bars represent mean±SEM (Student t-test, *P<0.05). (C and D) Monocytes from 8 CLL patients were treated with ROCK, Rap1 and Rac1 inhibitors for 30 min before stimulation with lenalidomide 1 μM or DMSO for an additional 20 min and measurement of the F-actin content. Quantification of staining, as mean fluorescence intensity value obtained from individual cells from 5 different fields at 400X magnification, is normalized on control (100%, inhibitors-untreated DMSO-treated monocytes). Lenalidomide mediates actin polymerization through the activation of RhoA, Rac1 and Rap1 GTPases. (C) One representative case. (D) Histograms represent mean±SEM of 7 independent experiments (Student t-test, *P<0.05).