Identification of a positive and a negative RARE in the OLFM4 promoter. (A) The potential retinoic acid responsive elements (RAREs) and retinoid X responsive elements (RXREs) binding sites identified by Genomatix software in the proximal promoter of the OLFM4 gene are underlined. The bold characters represent nucleotides that were deleted. (B) OLFM4 promoter activity in HL-60 cells transfected with various promoter constructs and then treated with either vehicle or ATRA. Luciferase reporter activities of OLFM4 promoter with serial RARE or RXRE/RORE deletions were analyzed with a dual-reporter system. The black boxes represent RARE or RXRE/RORE binding sites. The gray boxes represent corresponding deleted sites. Values were normalized to Renilla luciferase internal controls. Data represent the mean ± SD of 3 independent experiments performed in triplicates. *P < .05, compared with corresponding wild-type (WT)–Luc control.