SBDS protein expression in peripheral blood lymphocytes. (A) A polyclonal antibody against the terminal 18 amino acids of the SBDS was generated in rabbits with adequate sensitivity and specificity at high (Hi, 1:500) and low (Lo, 1:2,000) dilutions, recognizing a protein with ∼31 kDa. (B) By Western blot, SBDS expression was evident in HeLa cells and peripheral blood lymphocytes from healthy controls, partially diminished in SBDS heterozygous aplastic anemia patients, and undetectable in patients with SDS. (C) FLAG-tagged SBDS (FLAG-SBDS-WT) and FLAG-tagged construct of SBDS N-terminal 84 amino acids (FLAG-SBDS-84X) were transfected into HEK 293T, but only the full-length protein was expressed (left panel), whereas in the cell-free rabbit reticulocyte expression system (RRL), both products were expressed.