Figure 2. L-Arg depletion induces ER stress in Jurkat cells and peripheral blood mitogen-activated T cells. (A) Cells were incubated with (C) or without L-Arg for the indicated times, and then total RNA was isolated and subjected to RT-PCR using specific primers for the XBP1 gene. PCR amplicons were incubated with PstI, and then run in agarose gel electrophoresis and stained with ethidium bromide. Only cDNA derived from sXBP1 mRNA was not cut with PstI, because of the loss of a 26-bp intron in response to ER stress. The positions of the amplification products uXBP1 and sXBP1 are indicated. (B) Jurkat and peripheral blood mitogen-activated T cells were incubated with (C) or without L-Arg for the times shown, and then cells were analyzed by immunoblotting with antibodies directed against the indicated proteins. Total ACTB was used as a loading control for western blots. Data shown are representative of three experiments performed.