Increased GF receptor expression and GF-mediated JAK/STAT signaling in AML CD34⁺ cells. (A) Expression of mRNA for growth factor receptors in AML (n = 24) and cord blood (n = 11) CD34⁺ cells, assessed by quantitative polymerase chain reaction. (B-C) Correlation between (B) FLT3 and (C) c-KIT mRNA expression (log₂) and pSTAT3 expression (log₂) in AML CD34⁺ cells. (D) Expression of pSTAT3 in CB CD34⁺ cells following exposure to FL (1 ng/mL) and SCF (200 pg/ml) (n = 3). (E) Expression of pSTAT3 in AML CD34⁺ cells (AML 600, 987, and 1050) following FL and SCF exposure (n = 3).