Rosa26 rtta mice

H2B-EGFP mice, Rosa26-rtTa mice and Rosa26-tdTomato mice were obtained from the Jackson Laboratory. K19^CreERT2 mice were kind gift from Guoqiang Gu and Cedric Blanpain. Both male and female mice with mixed background (C57BL/6 and CBA) between the ages of 5 days and 6 months were used in the experiments. Nursing mothers of bigenic R26-rtTa-H2B-EGFP pups received doxycycline in the drinking water (2 g/l, AppliChem), supplemented with 5% sucrose. At P21 the K19^CreERT2/R26-tdTomato mice were injected intraperitoneally with 2 mg of tamoxifen in rapeseed oil. All procedures involving animals were conducted according to the guidelines approved by the Commission of Laboratory Animal Licenses at the Estonian Ministry of Agriculture (license no 25 and no 88).

Rosa Vav1 transgenic mice were generated by crossing Rosa26-rtTA mice (purchased from Jackson laboratories, Bar-Harbor, ME, USA) with tetO-wtVav1 mice, previously generated by Salaymeh et al. [22 (link)]. Briefly, human wild-type Vav1 was subcloned into a plasmid that encodes a Tet-O responsive bidirectional promoter (Teto7minCMV) driving expression of wild-type human Vav1 hooked to GFP (tetO-Vav1). TetO-Vav1 mice were produced by injecting the plasmid into C57BL/BALB/c blastocysts according to standard IVF protocol. TetO-Vav1 mice were crossed with Rosa26-rtTA mice to generate Rosa Vav1 mice (Figure 1A). To induce Vav1 expression in Rosa-Vav1 mice, Doxycycline (Dox, 0.5 mg/mL, Bio-Basic Inc., Markham, ON, Canada) was provided in the drinking water as a sucrose solution (3% w/v) to 1-month old mice. All experiments were approved by the Hebrew University Ethics Committee for animal use (#MD-19-15940-5).