Extended Data Figure 4. Lineage tracing of the Cdh5(PAC)-Cre^ERT2 (iECre) transgene in neonatal mice.

a–c, R26-LSL-RFP, R26-Cre^ERT2;R26-LSL-RFP, and Cdh5(PAC)-Cre^ERT2;R26-LSL-RFP neonates were induced with doses of tamoxifen on P1+2 (two total doses) and CD45⁺;RFP⁺ hematopoietic cell numbers in the spleen and peripheral blood assessed at P10. N≥5 per group. Error bars shown as s.e.m. and significance determined by one-way ANOVA with Holm-Sidak correction for multiple comparisons. ***indicates p<0.001; n.s. indicates p>0.05. Note that the number of labeled hematopoietic cells in Cdh5(PAC)-Cre^ERT2;R26-LSL-RFP animals is indistinguishable from R26-LSL-RFP negative control animals, while >90% of CD45+ cells were RFP⁺ in R26-Cre^ERT2;R26-LSL-RFP positive control animals. d, Anti-RFP and anti-PECAM immunostaining of P10 hindbrains from Krit1^fl/fl;R26-LSL-RFP negative control and iECre;Krit1^fl/fl;R26-LSL-RFP was performed to identify Cre⁺ descendants at the site of CCM formation. Note that all RFP⁺ cells in iECre;Krit1^fl/fl;R26-LSL-RFP animals are PECAM⁺, consistent with endothelial-specific Cre activity. Asterisk indicates CCM lesion. Results are representative of ≥ 3 per group. Scale bars, 100 μm.