Table 1B.

¹³C fractional enrichments of GLN C4 in the tumors. Calculation of a–e are from ¹³C NMR spectra of GLN C4 as described in the text (Materials and Methods). d and e correspond to the fractions that have [4,5-¹³C] and [3,4,5-¹³C] isotopomers respectively. a is the fraction that has no ¹³C. (b+c) together represents the contributions from the metabolism of [1,2-¹³C]acetate by peripheral organs to tumor GLN C4 ¹³C pool. FE is equal to (b+c+d+e) and corresponds to fractional enrichment of GLN C4 in the tumor.

Tumor type	a	b	c	d	e	FE	(b+c)/FE	(d+e)/FE
GBM	0.762	0.014	0.002	0.196	0.027	0.238	0.065	0.935
GBM	0.787	0.026	0.002	0.171	0.015	0.213	0.131	0.869
Breast metastasis	0.659	0.021	0.003	0.276	0.041	0.341	0.071	0.929
Lung metastasis	0.669	0.023	0.009	0.271	0.028	0.331	0.096	0.904