Genomic Markers Before and After Treatment of Actinic Keratosis With Imiquimod 3.75% Cream

Inclusion Criteria: * Adults at least 18 years old. * Subjects must be in good general health as confirmed by the medical history. * Subjects must be able to read, sign, and understand the informed consent. * Prior to imiquimod therapy, subjects must have at least 4-8 actinic keratoses on the face and/or scalp. * Subject must be willing to forego any other treatments on the face and/or scalp, including tanning bed use and excessive sun exposure while in the study. * Subject is willing and able to participate in the study as an outpatient, making frequent visits to the study center during the treatment and follow-up periods and to comply with all study requirements including concomitant medication and other treatment restrictions. * If subject is a female of childbearing potential she must have a negative urine pregnancy test result prior to study treatment initiation and must agree to use an approved method of birth control while enrolled in the study. Exclusion Criteria: * Subjects with a history of melanoma anywhere on the body. * Subjects with an unstable medical condition as deemed by the clinical investigator. * Subjects with non-melanoma skin cancer on the face and/or or scalp. * Subjects with any dermatologic disease in the treatment area that may be exacerbated by the treatment proposed or that might impair the evaluation of AKs. * Subjects who have previously been treated with imiquimod: on the face or scalp in the past 6 months; or outside of the study area within the past 30 days. * Women who are pregnant, lactating, or planning to become pregnant during the study period. * Subjects who have experienced a clinically important medical event within 90 days of the visit (e.g., stroke, myocardial infarction, etc). * Subjects who have active chemical dependency or alcoholism as assessed by the investigator. * Subjects who have known allergies to any excipient in the study cream. * Subjects who are currently participating in another clinical study or have completed another clinical study with an investigational drug or device on the study area within 30 days prior to study treatment initiation. * Subjects who have received any of the following within 90 days prior to study treatment initiation: * interferon or interferon inducers * cytotoxic drugs * immunomodulators or immunosuppressive therapies (inhaled/ intranasal steroids are permitted) * oral or parenteral corticosteroids * topical corticosteroids if greater than 2 mg/day * any dermatologic procedures or surgeries on the study area (including any AK treatments) * Subjects who have used any topical prescription medications on the study area within 30 days prior to study treatment initiation.