TWIST expression and interactions with p53 in primary CD34⁺ marrow cells and myeloid cell lines. (A) Primary CD34⁺ marrow cells from healthy donors and patients with MDS. Healthy CD34⁺cells (control) cultured without stroma (Not-CC) or with stroma contact (CC) showed no change in the expression of p53 or TWIST. In cells from patients with MDS, p53 showed prominent up-regulation on stroma contact (CC), whereas levels of TWIST declined. (B) Immunoprecipitation (IP) of TWIST from KG1a, MDS-L, HL-60, and PL-21 cell lysates. p53 was contained in the complex precipitated from all myeloid cell lines by anti-TWIST antibody; DJ-1 served as positive (+) and Stro-1 as negative (−) control. (C) IP as in panel B, but using KG1a cells without and with coculture, normalizing for TWIST content in the cell lysate. IgG indicates immunoglobulin G.