Ramos/STAT5 Reporter (GFP) cells are derived from the human B lymphocyte cell line Ramos by stably integration of a STAT5 GFP reporter construct. Ramos cell line was generated from a human Burkitt′s lymphoma which does not possess the EBV genome, has been widely used in cancer research, virus study and drug development. Ramos cells express CD19, CD20, and other B-cell markers, making them a useful model for B-cell studies and test the efficacy of monoclonal antibodies and CAR T-cell therapies targeting B-cell malignancies. Ramos/STAT5 Reporter (GFP) cells stably express GFP under the control of the STAT5 response elements, can be used for monitoring the activity of STAT5 signaling pathway.