Fig 1: RPL9 is downregulated in BRCA and suppresses cell proliferation while promoting apoptosis in BRCA cells. (A) Representative IHC images showing AIMP2 and RPL9 expressions in BRCA and adjacent normal tissues. (Left: ×200 magnification; Right: ×400 magnification). (B–C) mRNA expression levels of AIMP2 and RPL9 in 11 pairs of clinical BRCA tissues. (D) Expression of AIMP2 and RPL9 in human normal mammary cell line MCF10A and BRCA cell lines (ZR-75-1, MCF7, JIMT-1, MDA-MB-231, MDA-MB-468, and SKBR-3). (E–F) Validation of successful overexpression of RPL9 in BRCA cell lines MCF7 and JIMT-1. (G–H) CCK-8 assays demonstrated that RPL9 overexpression significantly inhibited the proliferation capacity of MCF7 and JIMT-1 BRCA cells. (I–J) RPL9 overexpression significantly increased the proportion of apoptotic cells in MCF7 and JIMT-1 BRCA cells.All experiments were performed with three independent biological replicates (n = 3). Error bars represent mean ± SD.ns: p > 0.05, *p < 0.05, **p < 0.01, ***p < 0.001.