PTEN and gastric cancer: In order to demonstrate that PTENP1 modulates PTEN expression via sponging miR-106b and miR-93 (miR-106b/miR-93∼PTEN ceRNA network), we carried out a novel ceRNA concentration gradient assay, in which a series of increasing amounts of the plasmid pCDH-PTENP1 or pCDH-mutPTENP1 containing disrupted seed sequence for miR-106b/miR-93 was co-transfected into GC cells with a constant amount of miR-106b or miR-93 mimics.