Fig. 1. P311 expression induces morphological changes in cells seeded at high density. (A) Semiquantitative RT-PCR showing low levels of expression of the Myc-tagged P311 transcripts in C3H10 cells that contain the Tet-On transactivator and a Tet-responsive mP311-myc transgene (mP311-myc) without (–) doxycycline (Dox) treatment, and increased levels of mP311-myc transcripts after induction with Dox (+). Control cells (C3H10 cells containing the Tet-On transactivator and a Tet-responsive empty vector) showed no expression of the mP311-myc transcripts. β-actin transcripts were used as a loading standard. (B,C) Control cells seeded at high density (10⁶ cells per 100-mm plate) have the typical spindle-shaped morphology of C3H10T1/2 cells in culture. (D,E) cells stably expressing P311 seeded at the same high density show a different morphology exhibiting cell enlargement and a dark perinuclear ring. Scale bars, 40 µm (B,D), 10 µm (C,E).