MCF-7 morphology - question (Jun/11/2007 )

Hi all,
I've got a question: I have MCF-7 from dwo different sources and they have different morphology. First cell line looks like at ATCC photo, but second has different morphology and growth very quickly (doubling about 20-30h). they grow on RPMI or DMEM with 10% FBS and MEM non essential. I attache the photo of these cells. Anyone observed this kind of morphology?

Best regards

The cells in the image do not look like MCF-7 cells to me.