This is a open label, non randomized, phase II , multicenter, prospective trial to evaluate the efficacy and safety of the combination of bortezomib and rituximab in patients with relapsed or refractory rituximab naïve or sensitive indolent non-follicular and mantle cell non-Hodgkin's lymphoma. Despite of the availability of treatment for this disease, this study is justified because no known therapies are really curative and it is necessary to look for new treatment options to improve the clinical outcome and prognosis of relapsed indolent lymphoma. This study is designed for patients not eligible for high-dose chemotherapy and autologous stem cells transplantation.