Effects of the oleanolic acid derivative on the morphology and membrane integrity of SMMC-7721 cells. (A) The morphology of SMMC-7721 cells was observed using fluorescence microscopy. Following treatment with the oleanolic acid derivative for 36 h, SMMC-7721 cells were observed under a fluorescence microscope. (a) Blank control; (b) DMSO; (c) 7 µM oleanolic acid derivative; (d) 9 µM oleanolic acid derivative; (e) 11 µM oleanolic acid derivative. (B) The membrane integrities of SMMC-7721 cells were analyzed by annexin V-FITC/PI staining. Following treatment with the indicated concentration of the oleanolic acid derivative or vehicle (0.11% DMSO) alone for 12, 24, or 36 h, the SMMC-7721 cells were stained with annexin V-FITC/PI and then were observed under a fluorescence microscope. All images were captured at magnification, ×100. FITC, fluorescein isothiocyanate; PI, propidium iodide; DMSO, dimthyl sulfoxide.