KLF4 and Burkitt lymphoma: We were likewise unable to detect KLF4 protein expression in any of the EBV-infected B cell types that we examined by immunoblot analysis (Fig 11), including Burkitt lymphoma cell lines with various forms of EBV latency and EBV-transformed lymphoblastoid cell lines, and did not detect KLF4 expression (by IHC analysis) in the lymphoid areas of normal human tonsil and spleen.