Please be noted, email format of correspondence authors of the Questionable paper 1 and 2 were “manipulated” to be similar. Both providers are 126.com and both are beginning with the abbreviation of address followed by short underlines.
Questionable Paper 1: Tumor necrosis factor alpha gene -308G>A polymorphism association with the risk of esophageal cancer in a Han Chinese population. Genet. Mol. Res. 15 (2): gmr.15025866
Questionable Journal: Genetics and molecular research (Impact factor 0.764)
(Questionable) Original Paper 1：Tumor necrosis factor-alpha gene −308G > A polymorphism alters the risk of hepatocellular carcinoma in a Han Chinese population. Diagn Pathol. 2014
Original Paper 2：Association between Tumor necrosis factor-alpha gene polymorphisms and prostate cancer risk a meta-analysis. Diagn Pathol. 2014
When using someone else’s work, you must indicate you have borrowed the idea by giving a citation. Besides, if a source’s exact words have to be copied, quotation marks must be given. However, verbatim copy of large sections of text (including a few sentences, whole paragraph, and several paragraphs) is moderate to most severe type of plagiarism whether or not that work is cited or quotation marks are used, even though the original sources are from author’s own publications.