1. Supplemental figure1 89101112131415 Age (weeks) Up to 39 Systemic DMBA Tumor detection Collection A D C loxP AREx2-FAREx4-R Exon 4 Exon 2 Exon 3 Exon 2 Exon 4 wt AR Ex3∆AR S1: A) Experimental design for systemic DMBA exposure. At 8 weeks of age both ARKO and WT female and male mice were given 1 mg DMBA in 100 μl of sesame oil by gavage, weekly for 6 weeks. Mice were followed up to 9 months of age for emergence of skin papillomas. B) Experimental design for two-stage carcinogenesis protocol. At 7 weeks of age the back of the ARKO and WT female and male mouse back was shaven and treated with single topical dose of 40 µg DMBA (in DMSO) followed by twice weekly topical treatment with 50 µg TPA (in DMSO) for 15 weeks. Mice were followed up to 7 months of age for emergence of skin papillomas. C) Expression of WT and mutated, exon 3 deleted Ar (ArΔEx3) was analyzed as previously described (20), with forward primer located at exon 2 (AREx2-F) and reverse at exon 4 (AREx4-R) of Ar. D) The PCR produces a WT Ar product of 284 bp and an exon 3 deleted product of 174 bp. Only ArΔEx3 product was detected in ARKO skin (shown for males). Neg = no template control. 7 8 910 1112 1314 Age (weeks) Up to 28 Topical DMBA Tumor detection Collection B 15 Twice weekly topical TPA Ladder (bp) Neg 400 200 WTARKO

2. WT A MaleFemale ARKO WT ARKO Supplemental figure 2 S2: Representative photos of H&E staining for skin structure (A) and masson-trichome staining of collagen layer (B) in WT and ARKO male and female skin at eight weeks of age. Female Yiwei Female Yiwei B

3. S3: A) Cumulative proportion of WT Sox, ARKO Sox, WT Cmv and ARKO Cmv male mice with skin cancers. No significant difference was found between WT Sox and WT Cmv (p=0.522; N =16) or ARKO Sox and ARKO Cmv (p=0.709; N≥13). B) Cumulative proportion of WT Sox, ARKO Sox, WT Cmv and ARKO Cmv female mice with skin cancers. No significant difference was found between WT Sox and WT Cmv (p=0.448; N≥18) or ARKO Sox and ARKO Cmv (p=0.699; N=17). Data are shown as percentage of tumor-positive mice after the last DMBA challenge. The statistical analyses were performed using Kaplan-Mayer Survival analysis (Mantel- Cox test). Supplemental figure 3 B A Skin cancer - Males % Tumor positive Weeks Skin cancer - Females % Tumor positive Weeks