APRIL induces expression of cyclin D1 and phosphorylation of Rb. (A) Karpas cells were stimulated for the indicated times with APRIL and analyzed for expression of cyclin D1, p27, c-myc, and phosphorylation of Rb. (B) Karpas cells transfected with control or TACI siRNA were treated with APRIL for indicated times and analyzed for cyclin D1 expression. (C) Karpas cells were treated with the indicated doses of rapamycin, and then stimulated with APRIL for 180 minutes, and analyzed for cyclin D1 expression and Rb phosphorylation. (D) CD19⁺ FL B cells were treated with APRIL for the indicated times and analyzed for expression of cyclin D1, p27, c-myc, and phosphorylation of Rb. Data from a representative patient are shown (n = 3). Densitometric values are listed below each blot.