YY1 is essential for the survival and growth of MM tumors.

<p>(<b>A</b>) KMM1 cells were infected with lentiviruses expressing control-ShRNA or Sh-RNA targeting YY1. 48 hours post infection lysates were analyzed by immunoblotting for the efficiency YY1 silencing as indicated. (<b>B</b>) KMM1 cells were infected with lentiviruses expressing control-ShRNA or ShRNA targetting YY1. 5 days later viability was measured by flow cytometry upon staining with Annexin-V and 7AAD. Numbers in the quandrants represent % of cells that are positive or negative for Annexin-V and/or 7AAD. A representative figure from 3 independent experiments was shown. (<b>C</b>) KMM1 cells were infected with lentiviruses expressing control-ShRNA or YY1-ShRNA. Two days later cell viability was measured to be equal between the control-Sh and YY1-Sh cells. 3×10⁶ cells were subcutaneously injected in nude mice as indicated (Solid arrows indicate injection of control cells where as dotted arrows indicate injection of YY1-depleted cells). Mice were euthanized when the tumor size has reached to a size about 1 cm. (<b>D</b>) KMM1 cells were infected with lentiviruses expressing control-ShRNA or YY1-ShRNA. 24 hours after infection cells were washed and 2000 cells for both control-ShRNA and YY1-ShRNA were seeded in methylcellulose cultures. Colonies were counted 10 days later and plotted as indicated. (<b>E</b>) Colony pictures were taken by a Axiovert S100TV microscope and were shown as indicated. Note that depletion of YY1 had completely impaired colony formation by MM progenitor cells.