Figure 5. TAp73 expression affects the methionine cycle.

A significant increment in the methyl-donor SAM correlates with an increase in its demethylated byproducts S-adenosylhomocysteine and cystathionine. Cysteine, the downstream metabolic product of cystathionine, also shows a robust accumulation in induced cells; although we cannot exclude that cysteine accumulation results from increased uptake from growth medium. Finally, we detected an upward trend in the methylated compound 5-methyltetrahydrofolate. Overall these changes suggest that TAp73 might regulate 1-carbon metabolism and epigenetic through availability of the methyl donor SAM. **p < 0.05; *0.05 < p < 0.1.