COL10A1 and osteopetrosis: In contrast, the Col10a1-Cre;Ctnnb1EX3fl/fl;ROSA26R-Tomato (X/ΔEXTomato) mice with stabilized β-catenin showed delayed primary ossification and developed an osteopetrosis-like phenotype after birth, opposite of the X/CKOTomato mice (Fig. 1C and Supplementary Fig. S3a–c).