C3 and kidney cancer: Interestingly, our study revealed increased levels of proteins of the C3/C5 axis, namely, CFB (FC = 1.7, p = 0.004), and C3 (FC = 1.3, uncertain value), C4B (FC = 1.5, uncertain value), Clu (FC = 1.4, p = 0.065), which is consistent with the literature data on prognostic significance of these factors in human kidney cancer (Xi et al., 2016; Netti et al., 2021; Reese et al., 2020).