IGHG1 and renal cell carcinoma: In particular, this would explain why high levels of CD70 expression (66) as well as immunoglobulin production and active isotype switching has paradoxically been associated with poor prognosis in RCC (75) and, strikingly, why the top-three-scoring differentially expressed genes IGHG1, IGLV3-1 and IGHG3 for the MitoLow plasma cell cluster (Supplementary Table 1) serve as a strong negative prognostic marker for RCC (76).