*2.11. Protein Isolation from Culture Media*

The cells were cultured with DMEM + 1% P/S differentiation media for two days, centrifuged at 5000× *g* for 5 min, and the supernatant was then incubated with 1.3% potassium acetate (Sigma Aldrich) for 1 h at 4 ◦C. The mixture was centrifuged at 1500× *g* for 10 min, the supernatant was discarded, and the pellet washed with 100% acetone (Merck, Darmstadt, Germany). The isolated proteins were then dried, and Western blot analysis was performed by adding buffer with protease inhibitor cocktail (Thermo Fisher Scientific).
