The invention pertains to a method of treating melanoma by administering to a subject in need thereof, a composition comprising a therapeutically effective amount of an inhibitor of PKC-ζ and/or PKC-ι. Non-limiting examples of an inhibitor of PKC-ζ and/or PKC-ι include ICA-1 and ACPD. The invention also provides PKC-ζ and/or PKC-ι as biomarkers for identifying a melanoma in a subject as likely to be responsive or non-responsive to a therapy using an inhibitor of PKC-ζ and/or PKC-ι. Accordingly, a method of identifying a subject having a melanoma as being responsive or non-responsive to a melanoma therapy with an inhibitor of PKC-ζ and/or PKC-ι based on the levels and/or activity of PKC-ζ and/or and/or PKC-ι mRNA or protein in the melanoma cells from the subject are also provided.
