To deplete cells of Ire1 or XBP-1 by RNAi, we transfected 3 × 10 4 cells with 150 ng total of a mixture of four different siRNAs (QIAGEN). After 48 h, we treated cells with DTT and/or 1NM-PP1, and purified RNA as described in the next section. We typically attained 90% knockdown as measured by qPCR.