One of the most important goals in the continuous struggle against cancer is early detection of the disease by a simple method that can be used in routine laboratory practice. According to several recent reports, early detection may be achieved by monitoring alterations at several microsatellite loci containing tri- and tetranucleotide repeats. The method relies on comparison of the intensity of allele bands in cancer tissue, plasma, and lymphocytes of a patient. Microsatellite instability is typically detected by labeling the DNA with a radioactive probe or a fluorescent dye followed by electrophoresis on 20-40-cm-long denaturing polyacrylamide gels. In this study, we show that loss of heterozygosity at the ACTBP2 locus in lung cancer patients can be detected using the Elchrom electrophoresis system and just 4-cm-long precast Spreadex gels.