NR2F1 and breast cancer: Nuclear receptor subfamily 2 group F member 1 antisense RNA 1 (NR2F1-AS1) is a natural antisense transcript (NAT) lncRNA that has been reported to serve as a carcinogenic factor in several types of malignant tumors, including HCC [14, 15], osteosarcoma [16], endometrial cancer [17], colorectal cancer [18], and breast cancer [19, 20].