As a prime example, one of the author's (Bruno's) recent aptamer development projects for detection of the cancer biomarker (ERK2) resulted in “clean” aptamer-magnetic bead pull-down of ERK2 from human serum as confirmed by gel electrophoresis and mass spectral analysis (Figure 1), because the aptamer was selected in diluted serum (Bruno, 2017b). Here, MAPK1 is linked to cancer.