This can be traced in contrasting pairs such as miR-19a/PTGER2 (pancreatic tumor); miR-421/PTGER2 (uterine tumor); miR-590/PTGFR (uterine and breast tumor); miR-20a/PTGER3 (uterine tumor) (Figure 5). This evidence concerns the gene PTGER2 and breast neoplasm.