4.9. Mouse Xenograft Tumor Growth Assay

Athymic nude mice (4- to 6-week-old females) were obtained from Envigo Laboratories (Indianapolis, IN, USA). All animal procedures and maintenance were conducted in accordance with the institutional guidelines of the University of Wisconsin-Madison. The Ethic code for that study is: UW-M005805. Mice were injected with 2 × 10⁶ cells (MDA-MB-231 parental or MDA-MB-231 YBX1 knockout clone 5) in both dorsal flanks. Tumor volume measurements were evaluated using digital calipers and calculated twice per week from day 7 after tumor cell injection using the following formula: π/6 × (small diameter)² × large diameter.