Relative FLT3 and FLT3L expression in childhood ALL with and without MLL gene rearrangements. (A) Relative mRNA expression of the Fms-like tyrosine kinase 3 (FLT3) as determined by quantitative real-time PCR (TaqMan) in infants with MLL (n = 41) and both infants (n = 8) and noninfants (n = 22) with ALL harboring germline MLL genes. (B) Relative FLT3 ligand (FLT3L) expression in primary infant MLL (n = 33), infant ALL (n = 4), and noninfant ALL (n = 10) samples. ○ indicates individual patients; and —, median expression values. Differences in FLT3 and FLT3L expression between 2 patient groups were statistically analyzed using the Mann-Whitney U test. NS indicates that P was higher than .05 in all comparisons.