(A) Correlation of FPGS activity (pmol MTX-Glu₂ formed/h/10⁶ cells) with accumulation of MTX-Glu_4-6 (expressed as pmol MTX-Glu_4-6/10⁹ cells). (B) Correlation of FPGH activity (nmol MTX formed/h/10⁶ cells) with accumulation of MTX-Glu_4-6 (expressed as pmol MTX-Glu_4-6/10⁹ cells). (C) Correlation of the ratio FPGS/FPGH activities expressed per 10⁶ cells with accumulation of MTX-Glu_4-6 (expressed as pmol MTX-Glu_1-6/10⁹ cells). Spearman rank correlation coefficients are presented for the total group. Statistical parameters for c/preB-ALL, T-ALL, and AML samples are presented separately in Table 3. (•), c/preB-ALL; (⧫), T-ALL; (▪), AML.