Looking for cell surface markers. - (Oct/28/2011 )

I am doing a Flow expt on ARP19 cells and HEK293T cells.
Can someone please tell me what I can use as positive control, like a cell surface marker on these cells?

CD71, transferrin receptor should be present on any cell.

Thanks!!

Is there any other receptor you can suggest that will be present on both cell types? One is eye cells and one is kidney.