Figure 3.

Effect of NRG1 peptides on expression levels of pAkt, ErbB2, and various melanocyte-specific proteins. (A) Left, after 8 days of treatment of darkly pigmented melanocytes with peptides, rhNRG1 or control (vehicle only), proteins were extracted and western blotting was used to detect levels of pAkt, ErbB2 and GAPDH (used as a loading control) as previously detailed (Choi et al., 2010). Numbers below each band reflect the quantitation of that band corrected for loading against GAPDH. Antibodies used were pAkt (Ser473) (1:1000; Cell Signaling Technology, Danvers, MA, USA), ErbB2 rabbit monoclonal (1:1000; Cell Signaling Technology) and GAPDH (FL-335) (1:10 000; Santa Cruz Biotechnology, Santa Cruz, CA, USA). Right, levels of tyrosinase, DCT, GP100, MART1, and GAPDH (used as a loading control). Numbers below each band reflect the quantitation of that band corrected for loading against GAPDH. Antibodies used were aPEP7h (1:5000) for TYR, aPEP8h (1:3000) for TRP2 and aPEP13h (1:3000) for GP100, as previously described (Virador et al., 2001), as well as MART1 (Ab-3) (1:1000; Thermo Fisher Scientific, Kalamazoo, MI, USA) and GAPDH (FL-335) as noted previously. (B) Proposed scheme of ErbB receptor and ligand binding in regulating growth and differentiation of melanocytes.