The FlexISH ALK/ROS1 DistinguISH Probe (PL161) is intended to be used for the qualitative detection of translocations involving the human ALK gene at 2p23.1-p23.2 and the human ROS1 gene at 6q22.1 in formalin-fixed, paraffin-embedded specimens, such as non-small cell lung cancer (NSCLC), by fluorescence in situ hybridization (FISH).