PPP1R21 and breast cancer: In this section of the work, we evaluate the possible functional value of rs10454142 PPP1R21 and 10 strongly coupled SNPs (r ≥ 0.80) in the following: (a) the liver (the main organ of SHBG synthesis in the organism [16]), (b) adipose tissue (the obesity-dependent association of the rs10454142 PPP1R21 with BC we found in this work), and (c) in general in the organism.