Cytotoxicity of IMMU-114 and rituximab on rituximab-resistant cell lines. Percentage of untreated values in MTT assay is shown. ¹IMMU-114 yields significantly more inhibition (P < .05) than rituximab when incubated without GAH. ²IMMU-114 yields significantly more inhibition (P < .05) than rituximab when incubated in the presence of GAH. ³Rituximab is significantly more effective (P < .05) in the parental lines than in the corresponding rituximab-resistant cell lines in Raji-2R, Raji-4RH, and SU-DHL-4–4RH.