KRT14 and neoplasm: To identify tumor-initiating SCC CSCs within their endogenous tumor microenvironment, Blanpain and colleagues (Driessens et al. 2012) adapted the earlier radionucleotide tracing methods to genetic lineage tracing by using tamoxifen on Krt14-CreER; Rosa26-fl-stop-flox-YFP mice to monitor skin tumorigenesis.