Passaging cells - (Dec/23/2014 )

Hi there, 

I just joined a new lab a couple months ago and I realized after I came that they passage their cells onto the same plate over and over again. Im assuming to save cost. Our data mostly comes from over-expressing or knocking down genes in cells and harvesting the protein and running on western. 

Is it normal to passage on the same dish?

The answer to this is no, it isn't normal to do this, and could easily be altering the cellular behaviour and hence expression patterns. For instance, cell attachment proteins will be left on the dish by the cells when they are lifted and re-plated, this could cause a decrease in expression of cell attachment and interaction proteins such as actin and cadherins.