CCNE2 and breast cancer: Roy et al. [33] showed that the chemotherapeutic agent trastuzumab can upregulate the expression of miRNA30b in breast cancer treatment and can achieve clinical therapeutic effects by targeting the cell cycle protein E2 (cyclin E2 [CCNE2]), leading to the blockage of the G1 phase of the cell, inhibition of cell proliferation, and increase of cell apoptosis.