Figure 1. Immunohistochemical staining of survivin in normal, pre-malignant (leukoplakia), and malignant (squamous cell carcinoma) tissue. (A) Normal oral tissue exhibited negative survivin protein expression. Original magnification, X50. (B) Moderately differentiated primary OSCC. Note the strong cytoplasmic immunoreaction for survivin. Original magnification, X100. (C) Survivin-positive case of leukoplakia. Note that strong positive immunoreaction for survivin was detected on the epithelial cell cytoplasm. Original magnification, X25. (D) The border between normal epithelium (right side) and the dysplastic lesion (left side) is indicated. Note that while no survivin expression was detected in normal epithelial cellular cytoplasm, strong survivin protein expression was evident in the lesion. Original magnification, X50. Bar = 100 µm.