Surface expression of death receptor proteins on quiescent CD34⁺ and cycling CD34⁺ and CD34⁻ CML cells. (A) Expression of Fas (CD95), TRAIL receptors DR4 and DR5 on quiescent CD34⁺ (QSC), cycling CD34⁺ (CD34+DIV) and CD34⁻ (CD34NEG) CML cells. *P < .05, **P < .01, ***P < .001 (n = 3 chronic phase, n = 4 accelerated phase, n = 1 blast crisis) (B) Effect of 10 nM bortezomib (BOR) treatment on the surface expression of TRAIL receptors DR4 and DR5, MICA/B, and major histocompatibility complex class I (HLA A,B, and C) on QSCs (mean of 2 separate experiments in each patient-donor pair; UPI 360, UPI 452, accelerated-phase CML and UPI 481, blast-crisis CML).