MEG3 interacted with p53 protein directly.

<p>(A) Western blot of p53 protein bound to in vitro transcribed biotinylated MEG3 incubated with HEK293 cell extract transfected with Flag-p53 vector. (B) Western blot of p53 protein bound to in vitro transcribed biotinylated MEG3 and deletion mutations RNA incubated with doxo-induced HepG2 cell extract (MEG3 deletion mutants M1, M1+M2, M3, M2+M3 are shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0139790#pone.0139790.g001" target="_blank">Fig 1A</a>). (C) In vitro transcribed biotinylated MEG3 retrieved purified GST-p53 but not GST. (D) RIP experiments were performed using an antibody against the p53 on extracts from doxo-induced HepG2 cells. The purified RNA was used for qRT-PCR, and the enrichment of the lncRNA MEG3 was normalized to GAPDH (upper, western blot of p53 protein after immunoprecipitation). Data was relative to mock-IP (IgG). (E) A series of p53 deletion mutants which were flag-tagged was treated as in (A), and association was detected by anti-Flag. Up represents successful expression of p53 deletion mutants. Down represents in vitro transcribed biotinylated MEG3 RNA was incubated with HEK293 cell extract which was transfected with p53 deletion mutants and associated proteins were detected by anti-Flag.