FOS and neoplasm: Thus, expression of menin in RAS-transformed NIH3T3 cells partially suppressed the RAS-mediated tumor phenotype in vitro and in vivo (Stalberg et al., 2004), and overexpression of menin in CHO-IR cells also suppressed insulin-induced AP-1 transactivation, and this was accompanied by an inhibition of C-Fos induction at the transcriptional level (Kim et al., 1999).