Patients in this study will have blood draws once before they take Neupogen and 6 times after they take the Neuopen (for a total of 24 hours). These patients will be in the hospital already and will not need to make additional trips back to have blood drawn. A total of about 5-6 tablespoons of blood will be drawn for this study. 15 obese patients and 15 matched, non-obese patients will be enrolled into this study.