are you doing orthotopic or sub cutaneous? If sub cutaneous the growth rate is very slow and sometimes no tumours grow without the matrigel. For orthotopic, tumours should grow, as they are in the site of origin.

Thank you for your answers Michael and Karen, we plan to make subcutaneous xenografts.

I would advise usinig Matrigel for this. MDA231 are slow growing.

Thank you Karen, finally we did it yesterday with Matrigel :)

Let's see the result within the next several weeks ^^

Let me know your progress. good luck :-)

Hi

In my opinion, MDA-MB-231 is one cell line that grows very slow after mixing with matrigel and SC injection to nude mice, let alone only media without matrigel. 

Good luck

Thank you for your answer David Lee