COS cells
![COS-7 cells, 40X magnification, confocal microscopy](/Images/godic/202501/06/COS-7_Cells_-_40X_Magnification_-_Confocal_Microscopy3039.jpg")
COS is a fibroblast-like cell line derived from monkey kidney tissue. COS cells are obtained by immortalizing CV-1 cells with a version of the SV40 virus that can produce large T antigen but has a defect in genomic replication. The CV-1 cell line in turn was derived from the kidney of the African green monkey.