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. 2021 Mar 12;4:332. doi: 10.1038/s42003-021-01857-0

Fig. 4. Forced expression of Creb5 in deep zone articular chondrocytes confers competence for EGFR and TGF-β signals to induce expression of Prg4.

Fig. 4

a, b EGFR and TGF-β signals synergistically induce expression of Prg4 in SZCs. SZCs were treated for 2 days with TGF-β2 (20 ng/ml) and TGF-α (100 ng/ml), as indicated. a Gene expression was assayed by RT-qPCR and normalized to Gapdh. Error bar indicates standard error of the mean (n = 2 technical repeats). Similar results have been obtained in three independent biological repeats. b Western analysis of proteins in SZCs cultured in either the absence or presence of TGF-β2 (20 ng/ml) and TGF-α (100 ng/ml). Similar results have been obtained in two independent biological repeats. c Forced expression of Creb5 in DZCs promotes synergistic induction of Prg4 by TGF-α and TGF-β2. DZCs were infected with a lentivirus encoding doxycycline-inducible Creb5. After selection in G418, the cells were cultured in either the absence or presence of doxycycline (1 μg/ml), TGF-β2 (20 ng/ml) and TGF-α (100 ng/ml), as indicated for 3 days. Gene expression was assayed in both the iCreb5-DZCs (lanes 1–7) and in control SZCs (lanes 8 and 9) by RT-qPCR and normalized to Gapdh. Error bar indicates standard error of the mean (n = 2 technical repeats). Similar results have been obtained in three independent biological repeats.