SOX2 and non-Hodgkin lymphoma: Double-staining was performed with both Sox2 and a second tumor-specific marker (CD20 for NHL-CNS; CAM5.2 for carcinomas; HMB45 for melanoma) on the remaining 20 metastatic cases to determine whether the Sox2-immunopositive cells might be part of the neoplastic cell population (Figure 3).