A proof-of-concept study has been carried out on CCRF-CEM cells (human acute lymphoblastic leukaemia T cells which overexpress protein tyrosine kinase 7 (PTK7)) using AAPs based on a conformation-switchable sgc8c aptamer, targeting PTK7 [207], labelled with a fluorophore/quencher pair [231]. This evidence concerns the gene PTK7 and acute lymphoblastic leukemia.