Fig. 7. Constitutive expression of human Evi1 in P19 cells results in an altered expression of neural and mesodermal markers. Expression of transcription factors (Mash1, Ngn1, and NeuroD), TrkA, and ActivinßA were detected by the semiquantitative RT-PCR method as described (24) . Wild-type P19 EC cells (P19), vector-transfected P19 clones (mock), and Evi1-transfected clones (clones D2, D5, C1, and C3) were grown as monolayers in the absence of RA, and control P19 cells were cultured 4 days after RA treatment [day 4; P19 RA (+)]. The amount of RNA in each reaction was normalized with transcripts of the 36B4 gene that is unresponsive to retinoid treatment.