Long-term exposure to relaxin does not stimulate proliferation in MDA-MB-231. Proliferation of MDA/EGFP and MDA/RLN2 transfectants was determined with (a) bromodeoxyuridine (BrdU) and (b) NADPH2-dependent MTT proliferation assays. Experiments were performed in triplicates and shown in the graph as mean ± SEM. The t-test features of the SPSS 10.0 software were employed to calculate for statistical significance of MDA/RLN2 compared with MDA/EGFP. p < 0.05 was marked in the graph as reduction (*) or as increase (#). **p < 0.005. (c) A luminometric ATP assay was performed to assess the metabolic activity and no changes were determined in MDA/RLN2 compared with MDA/EGFP clones.