To investigate the effect of derlin-1 on the apotosis-inducing potential of ER stress in breast cancer cells, derlin-1 siRNA was introduced into SKBR-3 cells to inhibit the expression of endogenous derlin-1, followed by flow cytometry analysis of apoptosis in cells treated with or without 300 nM TG for 24 hours. This evidence concerns the gene DERL1 and breast cancer.