Fig. 6

The inhibition of ERK blocked the proliferation and proliferation of SCs. A-a Phosphorylation of ERK was promoted in the USCs-Exo group. A-b Expressions of mRNAs downstream the ERK pathway were promoted in the USCs-Exo group. B After 24 h of using ERK inhibitor, PD98059, the percentage of proliferative SCs decreased obviously, as indicated by the EdU test. C-a Proliferation ratio of SCs in the EdU test. C-b CCK-8 test showed that PD98059 inhibited the proliferation of SCs. D After 24 h of using PD98059, no myotubes were observed in the PD98059 or USCs-Exo + PD98059 group compared with the USCs-Exo group (D-a, D-b, D-c). DES was stained green and MHC was stained red. Nuclei were stained blue. Myotubes were observed as stained DES, MHC, and arrowheads in bright field (BF). E Western blot analysis detected the expression of myogenic proteins in SCs under different cultivation conditions (× 100 magnification)