Fig. 4. Inhibition of CaMK activity diminishes the specification of P19 cells to cardiomyoblasts. P19 cells were aggregated with and without DMSO in the presence or absence of the CaMK inhibitor KN-93 or its non-functional analogue KN-92. (I) Total RNA was harvested on day 0 (lane 1); day 3 without DMSO (lane 2), day 3 with DMSO (lane 3), day 3 with DMSO and in the presence of KN-92 at 10 µM or 7.5 µM (lanes 4 or 5, respectively), and day 3 with DMSO and in the presence of KN-93 at 10 µM or 7.5 µM (lanes 6 or 7, respectively). Northern blot analysis was performed with 12 µg of total RNA to detect expression of the transcripts indicated on the right. (II) P19 cells were treated with 2.5 µM, 5.0 µM, 7.5µM and 10 µM of KN-93 or KN-92 and the level of Gata4 expression was quantified by densitometry. Bars represent the densitometric measurement of Gata4 transcripts from one representative experiment relative to rabbit 18S cDNA.