Fig. 1. Cl-tetracycline-inducible expression of cyc-B2-HA mRNA and Cyc-B2-HA-associated Cdk activity in tobacco plants and in cultured cells. (A) Northern blot of mRNA samples from leaves from lines 1, 2, 4, 5 and 6 incubated with (+) or without (-) 0.1 mg/l Cl-tetracycline for 1 day. (B) Time course of cycB2-HA mRNA induction by 0.1 mg/l Cl-tetracycline in cultured cells generated from line 2. In both A and B the upper panel represents CycB2-HA mRNA and the lower panel represents control (cnt6) mRNA. (C) Western blot of total protein samples from cultured cells generated from line CycB2-HA-2, which was induced for 12 hours by indicated concentrations of Cl-tetracycline. CycB2-HA and Cdc2 protein were detected using HA-specific and PSTAIRE-specific antibodies, respectively. (D) Histone H1 kinase activity of immunopurified CycB2-HA-associated kinase and p13^suc1-bound Cdks from the extracts shown in C.