Chem-6 Parental Control Frozen Cells are designed for use as a negative control alongside our GPCR-expressing Ready-to-Assay Frozen Cells in the Chem-6, Chem-7, and Chem-8 backgrounds. Chem-6 cells lack endogenous expression of most GPCRs, although they endogenously express trypsin and thrombin receptors that may be used to confirm responsiveness of the cells in calcium assays. The Chem-6 cell line is adherent to tissue culture-treated surfaces and contains high levels of the promiscuous G protein Ga15 to couple many classes of GPCRs to the calcium signaling pathway.