TGFA and cancer: Substances such as growth factors (VEGF), oxygen, glucose, TGFα and TNFα; and Signaling pathways including EGFR and TNF are described as continuum fields in the cancer microenvironment (see subsection a.2 ‎0and ‎a.1), while individual discrete components (e.g. healthy, cancerous and endothelial cells) dynamically evolve in response to local circumstances like substance concentration.