Rituximab signaling is not compromised in RIT-INP formulation. (A) Time-dependent changes of p38 in CLL B cells activated by free G3139 and G3139-containing RIT-INPs. The p38 MAPK activation in CLL B cells treated by free G3139 (1μM) and RIT-INP–encapsulated G3139 (1μM) was monitored by Western blotting. (B) Partial inhibition of costimulation of free G3139 by cross-linking of rituximab with anti-Fc. Fold changes of costimulatory molecules on CLL B cells with treatment of G3139 (1μM), RIT (10 μg/mL), and anti-Fc (50 μg/mL) after 48 hours were measured by flow cytometry. Results are shown as means of n = 3 independent experiments. (C) Partial inhibition of costimulation of free G3139 with cross-linking of empty INP. Similarly, CLL B cells were treated by free G3139 plus empty RIT-INP for 48 hours and then the expressions of costimulatory molecules were measured by flow cytometry (n = 3, mean ± SEM). (D) The effect of CLL B cells cotreated by free G319 and empty RIT-INP on Bcl-2 down-regulation. Comparison of protein levels of CLL B cells treated by free G3139 (1μM) and G3139 (1μM) plus empty RIT-INP and RIT-INP–G3139 (1μM) were measured by Western blotting after 48 hours.