Fig. 5. Differences in ITPK1 expression in WT and CF MTEs and its impact upon synthesis of InsP₅ and InsP₆. (A-C) Quantitative PCR was used to assess the degree of ITPK1 expression in the two cell types, relative to the GAPDH control (A), as indicated in the Materials and Methods. Data represent mean ± s.e.m. of four experiments (P<0.002). Cellular levels of (B) InsP₅ and (C) InsP₆ (mean ± s.e.m. of five experiments) were determined as described in Fig. 2; levels of these two polyphosphates did not change following the addition of UTP (data not shown).