Additionally, we also analyzed several publicly available RNA-Seq datasets to investigate whether cell types highly expressing fractalkine would express both splice variants, but in human airway epithelial cells [54], differentiated human keratinocytes [55] and in human nasopharyngeal carcinoma cells [56], where fractalkine is significantly up-regulated, we also could not confirm the expression of the shorter transcript variant. This evidence concerns the gene CX3CL1 and nasopharyngeal carcinoma.