RFC4 and lung cancer: On the other hand, consistent with the notion that amplification of the 3q chromosome, where the RFC4 gene is located, is mostly seen in squamous cancers, the mRNA levels of RFC4 are averagely increased approximately 9.42-fold in LUSC, approximately 40.3% of which have RFC4 gene amplification in the TCGA lung cancer datasets; by contrast, RFC4 mRNA levels are increased approximately threefold on average in LUAD, and approximately 2.33% of LUAD samples have RFC4 gene amplification in the TCGA lung cancer datasets.