Expression of miR-23a was control by p53. A shows that induction of p53 by nutlin-3α up-regulates expression of miR-23a. HepG2, MHCC97L cells (p53-proficient) and Hep3B cells (p53-deficient) were treated with nutlin-3α (20 μM) for 24 h. The miR-23a expression was analyzed by qRT-PCR. Significant induction of miR-23a expression in HepG2 and MHCC97L but not Hep3B cells could be observed. B shows transcriptional activation of miR-23a induced by p53. Cells were exposed to nutlin-3α (20 μM) then the pri-miR-23a and pre-miR-23a expressions were analyzed by RT-qPCR; both primary and precursor form of miR-23a was up-regulated upon nutlin-3α treatment; C shows that suppression of p53 down-regulated miR-23a. Cells were introduced with RNAi against p53 and significant reduced expression of miR-23a could be observed in cells in which p53 was repressed.