Cells were cultured with the drugs, milatuzumab (5 μg/ml), and GAH second antibody (20 μg/ml) as shown, then assayed using MTT. Percent inhibition of absorbance at 570 nm, relative to media only, was measured. ○, solid line, drug only; △, dashed line, drug + milatuzumab; □, dotted line, drug + GAH; ●, solid line, drug + milatuzumab + GAH. Error bars represent standard deviations of 4 replicates.