Fig. 1
Macroscopic and histological characterization of spontaneous and acute UVB induced melanomas from control and RXRαep−/−|TyrNRAS Q61K|Cdk4R24C/R24C mice. Mice with epidermal-specific Rxrα ablation in combination with Tyr-NRASQ61K and homozygous Cdk4R24C mutations have (a) spontaneous melanocytic growths; (b) larger melanocytic tumors with some degree of ulceration post single neonatal UVB treatment compared to mice with functional Rxrα. Lesions indicated by arrows. Histological analyses of melanocytic tumors from Tyr-NRASQ61K and Cdk4R24C mice and with functional (left panel) and ablated (right panel) Rxrα. Tyr-NRASQ61K /Cdk4R24C mice with epidermal-specific Rxrα ablation have (c) more pigmented lesions with minimal penetration into epidermal basal layer (inset); (d) greater degree of densely pigmented lesions with enhanced penetration into epidermal basal layer after acute neonatal UVB treatment. E, epidermis; D, dermis; HD, hypodermis. Scale bar =50 μm. e, f Increased epidermal thickness, and (g, h) higher radial growth phase (RGP) and vertical growth phase (VGP) of melanocytic tumors in RXRαep−/− |Tyr-NRASQ61K |Cdk4R24C/R24C mice with (e, g) no UVB treatment and (f, h) single UVB treatment relative to their respective controls. Statistical relevance indicated as follows; * = p < 0.05