TNFSF13 and neoplasm: The tumour microenvironment plays an important role in CLL, since neoplastic cells rely on survival factors such as B-cell activating factor (BAFF; TNFSF13B) and proliferation-inducing ligand (APRIL; TNFSF13), provided, inter alia, by non-neoplastic nurse like cells (NLCs) [2,9].