XBP1 and neoplasm: Lack of correlation with XBP1 in tumor cells is not surprising given the demonstration that XBP1 in immune cells (dendritic cells and T cells) plays a tumor‐promoting role (Cubillos‐Ruiz et al, 2017), hence highlighting the relevance of cell types and lineages in defining the role of UPR branches in the tumor microenvironment.