CM triggers IGF1R/IR and ERBB-family tyrosine phosphorylation in hESCs. (A) RTK array analysis of H1 cells stimulated by CM for 5 or 15 minutes. Tyrosine phosphorylation of IGF1R/IR and lower-intensity phosphorylation of ERBB (EGFR) family members was observed consistently. (B) RTK analysis of H1 cells stimulated by NCM and CM for 15 minutes. Increased ERBB3 phosphorylation was observed with CM stimulation. (C) RT-PCR analysis of IGF1, IGF2, IGF1R, and IR expression in H1 cells, and IGF1 and IGF2 expression in MEFs; ERBB1-4 expression in BG03 cells (and BG01 and BG02 cells; Figure S4); and HRG and ADAM19 expression in MEFs. Full-length gels are presented in Figure S4 online. (D) Flow cytometry of IGF1R, IR, ERBB2, and ERBB3 expression in H1 cells.