USP18 and breast cancer: The results shown in Figure 5A indicated that mRNA levels of EIF2AK2 (P<0.05), USP18 (P<0.001), DDX58 (P<0.001), RBL2 (P<0.0001), STAT2 (P<0.05), PGR (P<0.0001), S1000A9 (P<0.0001) and CCND1 (P<0.0001) were significantly higher in ER+- than in ER--breast cancer tissues while the expression level of S100A8 (P<0.0001) was significantly lower in ER+- than in ER--breast cancer tissues.