UBE2D2 and breast cancer: For example, one report observed the upregulation of circ-UBE2D2 in tamoxifen-resistant BC (80), while in another study the downregulation of circ-0025202 was evident in tamoxifen-resistant BC, with the upregulation of this circRNA suppressing the proliferative, migratory, and invasive activity of MCF-7 cells while enhancing their tamoxifen sensitivity and tendency to undergo apoptotic death (81).