Actin gfp mice and rag1 deficient

Breeding and all animal procedures were performed in accordance with UK Home Office regulations under project license PPL80/2531 and PPL70/9032. Female mice 6-12 weeks old were used in all experiments. Wild-type BALB/cJ, C57BL/6J, FVB/n, NSG and Nude mice from The Jackson Laboratory were provided by The Francis Crick Biological Research Facility. MMTV-PyMT mice on a FVB background were originally obtained from The Jackson Laboratory, actin-GFP mice and RAG1 deficient FVB/n mice were originally a gift from J. Huelsken laboratory (EPFL, Lausanne, Switzerland) and bred at the Francis Crick Institute. Gcsf knock-out mice were also a gift from the J. Huelsken laboratory and backcrossed to the FVB/n (N10) background. Sftpc-CreER^T2 mice on a C57BL/6J background were a gift from the J-H Lee laboratory (MRC Cambridge Stem Cell Institute). Rosa26-NICD-IRES-GFP mice^{26 (link)} on a mixed background were purchased from The Jackson Laboratory (stock 008159). Ela2-Cre knock-in mice were originally purchased from European Mouse Mutant Archive (EMMA). For experiments in which mice developed a primary tumour, the maximum tumour size did not exceed 1.5 cm, in compliance with project license PPL80/2531.