APLN and cancer: Most interestingly, PD-1, PD-L1 cancer immunotherapy pathways, antioxidant action of vitamin C, RhoGDI signalling, Apelin cardiac fibroblast signalling pathway and LXR/RXR activation pathways were downregulated significantly in older TG (> 12 M) compared with 3 M TG rats (Fig. 6b, c).