Hello Everybody

I am using KP mouse cell line to induce flank tumors in OT-I mice, but still can't get any palpable tumors although I have injected my mice two weeks ago. I used 10*104 and 5*104 in 100ul Media for inoculation. As I surfed the literature, the tumors should develop withing 2 weeks, but still there is no tumors grown in my animals. What is the usual time frame to observe tumors in OT-I mice? Is the inoculation density too low, that there will be no tumor growth? When can I stop the experiment with no tumor growth observed?

I would appreciate any suggestion and help