THTPA and neuroblastoma: He observed that, after incubation of cultured neuroblastoma cells with radioactively labeled sulbutiamine, the radioactivity increased more rapidly in ThTP and ThMP than in their precursor (ThDP), suggesting the existence of two ThDP intracellular pools: one high turnover pool precursor for ThMP and ThTP synthesis and one low turnover pool of ThDP associated with apoenzymes.