Fig. 4.

Lineage tracing technique. a–c Col2-expressing cells label a subpopulation of chondrocytes which could migrate to bone marrow underneath the growth plate and transdifferentiate into progenitor cells. a Col2-CreER mice were generated and bred with ROSA^mT/mG reporter mice or ROSA^tdTomato reporter mice. b Tamoxifen was intraperitoneally injected to the 2-week-old Col2-CreER; ROSA^mT/mG mice or Col2-CreER; ROSA^tdTomato mice for 5 consecutive days (1 mg per 10 g body weight) and mice were sacrificed at 4-week-old. c Col2-expressing cells were detected in articular chondrocytes, growth plate chondrocytes and cells located in bone marrow underneath the growth plate. d DNA barcoding technology was used for cell lineage tracing. Figure 4a, b²⁵⁶ and Fig. 4c²⁵⁷ were cited from our previous publications.