Effects of RSK2 inhibition on lenalidomide-mediated immune-modulatory activities. (A) Jurkat T cells (top panel) were pretreated with vehicle (control) and indicated doses of lenalidomide (Len, 1 μM) and BI-D1870 (BI, 0.25 and 0.5 μM) for 1 hour, and then stimulated with PMA (1 ng/mL)/ionomycin (Ion, 1 μg/mL) for 40 hours. The cells were fixed, stained with anti-IL-2–APC and analyzed by flow cytometry. The expression of IL-2 after different combination of treatment (from left to right) are shown. (B) The treated Jurkat cells were also harvested for analysis of IKZF1 expression by western blot. (C) Human PBMCs were pretreated with lenalidomide (1 μM) or BI-D1870 (BI), or a combination of both drugs for 1 hour and then stimulated with LPS (1 ug/mL). The supernatants were harvested and tested for TNFα production by ELISA.