Fig. 1.

MLL expression is increased in tamoxifen-resistant breast cancer. a, b Total whole cell lysates and RNA obtained from the tamoxifen-resistant cells and their parental cells were subjected to western blotting (a) and qRT-PCR analysis (b). Data presented as mean ± SEM (n = 3). *P < 0.05, **P < 0.01 and ***P < 0.001. c The GSE9893 data set was obtained from NCBI GEO [32]. The expression levels of MLL1, MLL2, MLL3, MLL4, SET1A, and SET1B mRNA in 155 patients with ESR1-positive breast cancer treated with tamoxifen for 5 years after surgery are shown by the log2 expression value. *P < 0.05 and ***P < 0.001. d ER-positive breast cancer patient data from the METABRIC and the GSE42568 data sets were analyzed in the CTGS website (https://ctgs.biohackers.net/) [36]. Patients were categorized into a low gene expression (lower quartile) group and a high gene expression (upper quartile) group. Disease-free-survival rate (%) was plotted for each group. To analyze statistical differences, Log-rank (Mantel–Cox) tests were performed