DDIT3 and pulmonary fibrosis: We found that TGFβ1 stimulation alone could not provoke significant ER stress, for the expression of Grp78 and CHOP was not increased even in the situation with a high concentration of TGFβ1 (up to 20 ng/mL) (Additional file 4: Figure E4A), indicating that myofibroblast transformation was not the reason for ER stress during pulmonary fibrosis.