TNF and nonpapillary renal cell carcinoma: Moreover, in ccRCC organ cultures, the downstream effects of TNFR2 signaling occur at much lower concentrations of TNF compared to TNFR1 signalling, consistent with in vitro data [80] whereby TNFR2 contribute to the effects of low concentrations of TNF, possibly serving to capture and pass TNF to the less abundant signalling (TNFR1) receptor.