RT-PCR products of BCR-ABL mRNA amplification of ET Ph-neg patients. (A) Lane 1, patient with b2a2 trascript; lanes 2 and 3, patients without BCR-ABL trascripts; lane 4, HL-60 negative control; lane 5, positive control extracted from K562 cells diluted 1:10⁵ with HL-60 negative cells; lane 6, molecular marker. PCR products of b3a2 trascript (B) and ABL (C) of five bone marrow samples. Lanes 1, 2, and 6, patients without BCR-ABL transcript; lane 3, positive control; lanes 4 and 5, positive patients; lane 7, HL-60 negative control.