In our previous studies, we found that splicing factors polypyrimidine tract-binding protein 1 (PTBP1), a member of hnRNP family, and SRp20, a member of SR protein family, were overexpressed in human ovarian and breast cancer cells and their expression were correlated with malignant potential of ovarian tumors but not with the stages of invasive tumors. Here, PTBP1 is linked to breast cancer.