NPC1 and nasopharyngeal carcinoma: Notably, when circCRIM1 expression was knocked down in S18 and HONE1 cells, the NPC cell morphology changed from a spindle-shaped or elongated mesenchymal form to an epithelial form (Additional file 1: Figure S6a-b), which indicated that circCRIM1 may function to induce NPC cell EMT.