Expressions of miR-21 and miR-34a in breast carcinogenesis and the influence of 3,6-dihydroxyflavone. Expression of microRNA-21 (miR-21) and microRNA-34a (miR-34a) in rat breast tissue was detected by quantitative RT-PCR at 0, 4, 8, 18 weeks after 1-methyl-1-nitrosourea injection, respectively. Data presented as mean ± standard deviation (n = 3). **P < 0.01 compared with control at each time point. #P < 0.05, # #P < 0.01 compared with control at 0 weeks.