 Currently, several approaches are being used to detect echinoderm microtubule associated protein like 4 gene (EML4)-anaplastic lymphoma receptor tyrosine kinase gene (ALK) rearrangement, but the performance of laboratories in China is unknown.     ///    Reliability Assurance of Detection of EML4-ALK Rearrangement in Non-Small Cell Lung Cancer: The Results of Proficiency Testing in China..     ///    "We prepared formalin-fixed, paraffin-embedded samples derived from the xenograft tumor tissue of three non-small cell lung cancer cell lines with different EML4-ALK rearrangements and used PTs to evaluate the detection performance of laboratories in China. "    ///    Our PT survey revealed that the performance and methodological problems of laboratories must be addressed to further increase the reproducibility and accuracy of detection of EML4-ALK rearrangement to ensure reliable results for selection of appropriate patients..     ///    "To evaluate the proficiency of different laboratories in detecting EML4-ALK rearrangement, we organized a proficiency test (PT). "