RFLAT-1 expression is regulated by MAP kinases and Mnk1. (a) PHA-activated PBLs were treated with medium (C), 4 μM SB203580 (SB), 4 μM SB202474 (SB-C), 10 μM PD98058 (PD), or both SB203580 and PD98058 (SB+PD). Western blots with anti–RFLAT-1, anti–ERK-1/2, and phospho-specific anti–ERK-1/2 Ab were performed. (b and c) Jurkat cells were electroporated with 5 μg of the RFLAT-1 expression vector alone or in combination with 10 μg of constructs expressing Mnk1. Western blots were probed with anti–RFLAT-1, anti–FLAG M2, and anti-Hsc70, and the amount of RFLAT-1 in the samples was determined as above. C, no DNA control. Results are representative of two independent experiments. *P < 0.05.