The analysis of the publicly available databases of transcriptomes of BC samples showed (Supplementary Table 5) that MMP1 gene expression negatively correlates with ELOVL5 gene expression (i.e., increases with a decrease in ELOVL5 gene expression) in tumor samples from patients with ER+ BC in seven analyzed data sets (in total, 10 datasets of ER+ BC were analyzed) and in only one dataset of ER−BC patients (in total seven datasets of ER−BC were analyzed). The gene discussed is MMP1; the disease is breast cancer.