 This Phase IbII, open-label, multicenter trial is designed to evaluate the safety, pharmacokinetics, and efficacy of dulanermin when combined with rituximab in subjects with follicular, CD20, B-cell Non-Hodgkins Lymphoma NHL that has progressed following a response of 6 months duration to a prior rituximab-containing therapy. The multicenter, international, randomized Phase II part of this study will commence only after the safety and available pharmacokinetic data from the Phase Ib part of the study have been evaluated by the Sponsor and have been provided to participating investigators and the FDA. 