While CL4 was not initially generated to specifically target EGFR, subsequent identification of the target led to further study to characterize the functional anti-cancer action of this aptamer in EGFR overexpressing tumors, supporting the idea that deeper understanding of molecular targets and interactors can lead to more specific therapeutic investigation of cell internalizing aptamers to uncover the intracellular signalling mechanisms that drive tumor growth, metastasis or survival. The gene discussed is EGFR; the disease is cancer.