High affinity aptamers for important signal transduction proteins,i.e.Cdc42-GTP,PAK1 and MRCKα were successfully selected in the low micro-to nanomolar range using non-SELEX,which is a new technique developed by Krylov et.al.utilizing capillary electrophoresis (CE) for a highly efficient affinity method to select aptamers for the desired molecular target.Aptamers are screened from a randomly generated population of DNA (or RNA) sequences through systematic evolution of ligands by exponential enrichment (SELEX),which involves several rounds of alternating steps of partitioning of candidate oligonucleotides and their PCR amplification.Non-SELEX is a process that involves repetitive steps of partitioning,known as non-equilibrium capillary electrophoresis of equilibrium mixtures (NECEEM),with no amplification between them.NECEEM also enables affinity studies of enriched libraries from every step of partitioning as well as the determination of binding parameters of the aptamers selected.Hence,it is of interest to select highly specific aptamers that recognize and bind to MRCK.These aptamers have the potential to work similarly as the small molecules for therapeutic intervention as well as being modified into chemical probes for cancer detection at a primitive stage.