Table 1. The main features of 4 selected studies of gene expression microarray data.

GEO Datasets	Platform	Samples in total	regions	Submission date	Citation(s) on
GSE18670	GPL570	24	Belgium	21-Oct-09	BMC Cancer 2012 Nov 16;12:527. PMID:23157946 [21]
GSE15471	GPL570	78	Romania	31-Mar-09	Hepatogastroenterology 2008 Nov-Dec;55(88):2016-27. PMID:19260470 [22]
GSE28735	GPL6244	90	USA	20-Apr-11	Clin Cancer Res 2013 Sep 15;19(18):4983-93. PMID: 23918603 [23] PLoS One 2012;7(2):e31507. PMID: 22363658 [24]
GSE58561	GPL14550	15	Norway	17-Jun-14	PLoS One 2014 Aug 22;9(8):e103873. PMID: 25148029 [25]