I would like to know, how does one induce a localized melanoma tumor with Braf/Pten Tyr Cre mice. I have tried inducing tumors with application of 5ul to 20ul volume of 5-100mM concentrated tamoxifen and observe for experimental time window of 40 days. All of the dose and concentration regimes result in melanoma tumors but are not consistent. Sometimes, I find a single localized tumor which is what I expect; while at other instances, I find additional small tumors making it hard to establish the model. I would like to know whether it is usual with these kind of genetic models or should I consider altering my dose and duration of Tamoxifen regimes to induce a single localized tumor.