CCND1 and breast cancer: They found that PCGF2 prevent trastuzumab resistance in HER2 positive BC.[26] Besides, they found that PCGF2 mediated Akt phosphorylation, and further promoted cyclin D1 expression and p27 phosphorylation in BC cell lines, through which BC cell growth was attenuated and G(1)-S phase transition was decelerated.[27] In addition, they reported that PCGF2 inhibited epithelial-mesenchymal transition of BC cells, the number and self-renewal activity of BC stem cells.[24,25] The study by Guo et al[28] indicated that PCGF2 repressed Akt activity in BC cells.