MUC5AC and cancer: A number of important targets are discussed, from thrombin—which, even if marginally involved in cancer-related pathologies, represents the most studied protein for aptamer recognition, typically exploited as a proof-of-concept in sensing strategies validation—to other important cancer biomarkers including platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), angiogenin and mucin.