NOS2 and cancer: Cancer cell iNOS/NO can activate signaling cascades mediated by proteins such as soluble guanylyl cyclase (sGC), hypoxia-inducible factor-1α (HIF-1α), epidermal growth factor receptor (EGFR), phosphoinositide-3-kinase/protein kinase B (PI3K/Akt), and extracellular signal-regulated kinases-1/2 (ERK1/2) [15,19,20,21,22].