In general, it takes about four to six months before tumors in these first-generation mice are sufficient in size to progress to a pharmacology study. On average, it takes four to eight weeks to determine whether the engraftment is successful. It usually takes about another four to 12 weeks before the tumor grows large enough to graduate to Phase II, the pharmacology study. When Certis scientists are confident tumor tissue is growing in mice, your Certis Patient Services Manager will notify you and your oncologist so you can begin planning your pharmacology study.Radiated tumor tissue will rarely engraft in mice[1]