tokens: RXR-alpha mRNA was present in untreated U937 cells , and levels increased after induction of differentiation with phorbol ester .
folded_tokens: rxr-alpha mrna was present in untreated u937 cells , and levels increased after induction of differentiation with phorbol ester .
labels: B-protein_molecule O O O O O B-cell_line I-cell_line O O O O O O O O O B-other_organic_compound I-other_organic_compound O