XBP1 and breast cancer: To determine whether XBP-1s directly binds to the TPP2 gene, we reviewed the ENCODE chromatin immunoprecipitation-sequencing (ChIP-seq) database and found that the TPP2 promoter displayed XBP-1 ChIP peaks in the breast cancer cell lines HS578T, MDA-MB-231, and T47D (Fig. 6H).