MMP1 and breast cancer: No remarkable heterogeneity was found either by MR-Egger or IVW methods for analysis of causal effect of BC on MMP-1/-7/-10/-12 (P>0.05) but MMP-3 (In GWAS data ieu-a-1128: MR Egger: P=0.03; IVW method: P=0.01) (Table 7).