MMP1 and breast cancer: The heat map (Fig. 7B) shows the significant correlations between ERO1 and PERK, EIF2 alpha, VEGFA, SERPINE1, PLAU, TFRC and MMP1 in basal tumors, confirming the strong association of ERO1 with the PERK branch of UPR and angiogenesis in basal breast cancer (Fig. 7B).