Moreover, the application of methods such as iontophoresis may improve the skin penetration of nanogels; Toyoda et al. fabricated cancer antigen gp-100 peptide KVPRNQ, demonstrating desirable accumulation of gp-100 peptide and nanogels in the epidermis, and, consequently, Langerhans cell numbers increased in the epidermis [100,121]. Here, PMEL is linked to cancer.