Figure 3.

Schematic comparing two models of tumor formation: the cancer stem cell and paracrine paradigms. In the cancer stem cell paradigm (left), a cell, which may be a stem cell, committed or differentiated cell becomes transformed into a cancer stem cell (CSC) upon exposure to an oncogenic stimulus. This transformed CSC proliferates to give rise to direct derivatives that compose the tumor mass. In the paracrine paradigm, upon receipt of the oncogenic stimulus the cell becomes secretory. The paracrine signals emanating from this mutated cell can be perceived by a competent surrounding cell that will become transformed to act like a CSC and become the cell‐of‐origin of the tumor. Abbreviation: CSC, cancer stem cell.