Figure 2D shows that overexpression of UCH-L1 in the ERα (+) breast cancer cells (MCF-7 and T47D) dramatically reduced the mRNA levels of CCND1 and AGR2; in contrast, knockdown of UCH-L1 in the ERα (-) breast cancer cells increased the mRNA levels of these two genes (Figure 2E; Figure S2C). Here, AGR2 is linked to breast cancer.