PTK7 and acute lymphoblastic leukemia: Aptamers against the extracellular region of PTK7 have been identified and one of them, an ssDNA sequence composed of 42 nucleotides named Sgc8c, was demonstrated to specifically eradicate Acute Lymphoblastic Leukemia (ALL) cells when coupled to doxorubicin, a drug used to treat this disease (Table 1).