(c) Re-introducing NRBF2 to NRBF2 KO MEFs reverses the vulnerability of cells to ER stress. NRBF2-CFP stably expressing cells were established in the NRBF2 KO background. Cells were treated with DMSO or 1 μM TP for 24 h then stained with PI and subjected to cell death rate analysis by flow cytometry. The cell death rate in CFP-positive (+) population (NRBF2-CFP expression) and negative (−) population (no NRBF2-CFP expression) were recorded and analysed, respectively. (Data are shown as mean±s.e.m., P values are indicated on the figure, unpaired Student's t-test, n=3). 