Moreover, DNA aptamers generated through SELEX against hepatocellular carcinoma (HCC) cells overexpressing the CD44E and CD44s variants [76], and against CD44 overexpressing CHO-K1 cells [77], have been utilized for delivering 5-Fluoruracil in a HCC xenograft model and for detecting circulating tumor cells in peripheral blood, respectively. The gene discussed is CD44; the disease is hepatocellular carcinoma.