PPP1R1B and breast neoplasm: In an attempt to discriminate between DARPP-32 and t-DARPP protein expression, we performed IHC analysis on duplicate breast tumor TMA with C-terminal DARPP-32 antibody, which recognizes both DARPP-32 and t-DARPP proteins, and N-terminal DARPP-32 antibody, which exclusively detects DARPP-32 protein.