Inclusion Criteria

DISEASE CHARACTERISTICS:

- Healthy volunteers who have not used topical medications to the skin of the upper
extremities, except for emollients or sunscreens, for at least 30 days prior to study
entry

PATIENT CHARACTERISTICS:

- Must agree to limit sun exposure as much as possible and wear protective clothing on
the forearms in place of using sunscreens or moisturizers

- Female participants must be surgically sterile by hysterectomy or post menopausal for
at least 1 year

- No signs of inflammation or irritation of the skin on the forearms

- No prior history of actinic keratosis or skin cancer on the forearm

- No known immunosuppression by virtue of medication or disease, including AIDS
patients

- No uncontrolled intercurrent illness including, but not limited to any of the
following:

- Ongoing or active infection

- Symptomatic congestive heart failure

- Unstable angina pectoris

- Cardiac arrhythmia

- No psychiatric illness/social situations that would limit compliance with study
requirements

- No invasive cancer within the past 5 years

- No skin conditions felt by the study physician to contraindicate enrollment
including, but not limited to, psoriasis or atopic dermatitis within a proposed
treatment area

PRIOR CONCURRENT THERAPY:

- See Disease Characteristics

- No concurrent therapy (e.g., retinoids, fluorouracil) on the forearms that may
interfere with clinical evaluations

- More than 30 days since prior and no concurrent or planned participation in another
clinical trial

- No concurrent oral supplemental niacin, by itself or in the form of a multi-vitamin
that exceeds 40 mg/day

- No concurrent oral prednisone

- No concurrent immunosuppressants/immunomodulators (e.g., cyclosporine,
chemotherapeutic agents, or biologic therapy)