Expression patterns of collagen and integrins during EB formation. (A) mRNA expression of collagen (Col1A1, Col1A2, Col3A1) and its integrin receptors (Itga1, Itga2, Itgb1) determined by semiquantitative RT-PCR. (B to D) Real-time PCR analysis of Col1A1, Itga1 and Itgb1, normalized to β-actin, in mESCs, miPSCs, and EBs (days 3 and 5). Experiments were performed in triplicate. *Significant at p < 0.05. (E) Immunostaining of collagen type I in miPSC-derived EBs on day 3. Scale bars = 200 μm.