KLF4 and nasopharyngeal carcinoma: In addition, we demonstrate that over-expression of CHOP is sufficient to induce both lytic EBV reactivation and epithelial cell differentiation in WT EBV-infected NOKs and NPC cells and show that this effect is mediated by CHOP activation of the differentiation-inducing transcription factors, KLF4 and BLIMP1.