There could also be another possibility in that the distal or proximal promoter region of SOX2 could suppress the expression of unidentified noncoding RNA, which shRNA for SOX2 does not target, leading to induction of CDKN1A. Recently, a noncoding RNA, SOX2 overlapping transcript (SOX2OT), has been identified as having a role in lung and esophageal cancer [27]. Here, CDKN1A is linked to esophageal cancer.