Slow growing cells (MCF-7 & MDA-MB231) - (Jun/27/2006 )

I am growing MCF-7 and MDA-MB231 cell lines at the same time.

The main problem I am having is, that both of the cells are not growing well.
They have been split 9 days ago, and still not confluent.

Is there any good idea or suggestion for that?

Some conditions are

1) I freshly made up new media (RPMI-1640 + 10% FBS)
2) The incubator has enough clean water.
actually the cells (osteoblasts) in the first and second shelf seem to be growing well.


I added 11ml of Pen/Strep solution in 1L media. Could it be that I overdosed the cells with
hight antibiotics?

Or do I need to add HEPES?

Please let me know...

I have used both cell types. MCF-7 grows in clusters and you really do not usually get confluent unless you seed alot of them on the plate. I dont recall any difficulty for MDA-MB231. I used DMEM+10% FBS for both, nothing special. May be the cell density was too low when you plate them?
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Thank you very much.
Also, I have been placing the cell at the bottom shelf of the incubator.
Right abover the water pan???

Do you think that'll be also one variable?

Not that I can think of. :-)

If the incubator is crowded that can sometimes affect the growth of the cells.

Have you checked for mycoplasma contamination?

hi DrPark ! i completely agree with genehunter-1, optimum seeding of cells is very important. low seeding usually slows down the growth rate and high seeding enhances the growth rate.
also removal of trypsin completely while subculturing is also imp. traces of trypsin might hinder the growth.
check for contamination.
i have not come across any cases where there is differential growth rate due to placing it in the lower shelf or upper shelf.
all the best

Thanks a lot to everyone who gave me nice comments.
Will keep them in mind.

Although, I still did not find the right answer.

I seeded well enough numbers of cells, half of which do not attach until the next day.
And day after day, more and more cells floats...

That's my problem.

I threw them away and am starting a new batch.
We'll see how it turns out this time...

Thanks