Using okadaic acid, a prototypical non-phorbol ester skin tumor-promoting agent, in transgenic mice expressing TAM67, Thompson and coworkers [98] observed that TAM67 was able to block okadaic acid-induced skin tumor promotion, which indicates that functional AP-1 is required for TPA induced tumor promotion in multistage mouse skin carcinogenesis in vivo. This evidence concerns the gene FOSB and neoplasm.