Betulinic acid, a triterpenoid isolated from Betula pubescens, enhances taxol chemosensitivity in breast cancer xenografts; the immunohistochemistry assay revealed that betulinic acid up-regulates the expression of BiP and CHOP, both alone or combined with taxol, confirming the results obtained in vitro [136]. Here, DDIT3 is linked to breast carcinoma.