Recombinant clonal stable CHO cell line constitutively expressing full length human CD37 protein, also known as GP52-40; TSPAN26; leukocyte antigen CD37 (Genbank #NM_001774). Surface expression of CD37 was confirmed by flow cytometry. Each stable clonal cell line was selected for different levels of CD37 expression, (High, Medium, Low), to mimic different stages of cancer target cells with various CD37 expression levels.