IL6 and central nervous system cancer: Here, we report that the introduction of the bi-functional N-terminal IL-6-HaloTag® outperforms the Rho-tag-HaloTag® in terms of cell surface expression of all investigated ORs, and also outperforms commonly used Rho-tag in terms of signaling of six out of seven investigated ORs, in both HEK-293 cells, as well as in the neuroblastoma x glioma NxG 108CC15 cell line.