B6.129 cg gt rosa 26sortm4 actb tdtomato

Mdm2-floxed mice (Mdm2^tm2.1Glo/J), mTmG mice (B6.129(Cg)-Gt(ROSA)26Sor^{tm4(ACTB-tdTomato,-EGFP)Luo}/J), Trp53-floxed mice (B6.129P2-Trp53^tm1Brn/J), Osx-Cre mice (B6.Cg-Tg(Sp7-tTA,tetO-EGFP/Cre)1Amc/J), and Vav-Cre mice (B6.Cg-Commd10^{Tg(Vav1-icre)A2Kio}/J) were purchased from The Jackson Laboratories. Experiments were conducted on age-matched mice between 8 and 12 weeks of age to ensure consistency and reduce variability in the results. Animals were housed in the MD Anderson Cancer Center animal facility, and all procedures using animals were approved by the Institutional Animal Care and Use Committee. For MDM2i treatment, mice were treated by oral gavage with DS5272 (Daiichi Sankyo, 100 mg/kg, three times/week) for two weeks and euthanized by asphyxiation with CO₂ for analysis 24 h after the last dose.

All mice were treated in accordance with guidelines of the Uniformed Services University of the Health Sciences (USUHS) and the National Institutes of Health Guide for the Care and Use of Laboratory Animals. Mice were socially housed as 2–4 mice per cage in 35 cm × 16.5 cm × 18 cm cages that contained enrichment objects and maintained a 12-h daytime light cycle (0600–1800) during which all experimental procedures were performed. The following mouse strains were obtained from the Jackson Laboratory (Bar Harbor, ME, USA): NG2CreER (RRID: IMSR_JAX:008538; B6.Cg-Tg(Cspg4-cre/Esr1*)BAkik/J">B6.Cg-Tg(Cspg4-cre/Esr1*)BAkik/J), ROSA^mT/mG (RRID:IMSR_JAX:007676; B6.129(Cg)-Gt(ROSA)26Sortm4(ACTB-tdTomato,-EGFP)Luo/J), and Thy1-YFP-16 (RRID:IMSR_JAX:003709; B6.Cg-Tg(Thy1-YFP)16Jrs/J">B6.Cg-Tg(Thy1-YFP)16Jrs/J). Mouse strains were bred as in-house colonies to generate experimental mice. First-generation offspring from NG2CreER and ROSA^mTmG breeders were used as NG2CreER;mTmG mice. The total number of Thy1-YFP-16 mice used was 15 (8 male, 7 female) and the total number of NG2CreER;mTmG mice used was 14 (10 male, 4 female). Male and female mice were combined for analyses after separate analyses showed no sex-based differences. Littermates of Thy1-YFP-16 mice or NG2CreER;mTmG mice were used for quantitative analyses. The number of mice for each condition in each experiment is provided in each figure legend.