In addition, for the invasion and colonisation of secondary tumour sites, cellular adaptability is crucial for these processes, accompanied by different signalling pathways, for example, the epithelial–mesenchymal transition (EMT), OPG/RANK/RANKL, TGF-β, IGF system, PI3K/Akt/mTOR, Wnt, Hippo, HIF-1, TNF, FoxO, JAK/STAT, PD-1/PD-L1, and EGFR pathways, among others. Here, HIF1A is linked to neoplasm.