This review highlights the TNFRSF member RELT (Receptor Expressed in Lymphoid Tissues), and its two paralogs RELL1 and RELL2 (RELT like 1 and 2, respectively), as there has been a recent increase in the number of reports implicating these three proteins in diverse processes affecting human health including cancer and immune system-related disorders. Here, RELL1 is linked to cancer.