PTBP1 and breast carcinoma: In breast cancer the 1.4 kb isoform of UCA1 is up-regulated (20-fold) and exerts its oncogenic effect, in part by the formation of a UCA1-hnRNP I (heterogeneous nuclear ribonucleoprotein I) complex, which results in suppression of p27 expression and promotes cancer cell proliferation [79].