Survival of irradiated zebrafish transplanted with unfractionated WKM or flow-sorted CD41-GFP^lo cells calculated by the method of Kaplan and Meier. This figure depicts survival at 90 days of fish transplanted with either varying numbers of CD41-GFP WKM cells or flow-sorted CD41-GFP^lo cells. Fish that were transplanted with 1000 CD41-GFP^lo cells showed much higher survival rate compared with control and the cohorts of fish received varying numbers of unfractionated CD41-GFP WKM cells. The P value .024 is for the log-rank test that indicates the survival distributions are significantly different.