Gene amplification and the cis-acting DNA elements responsible are well characterized in mammalian cells and provide an effective means of increasing protein production in cell culture. Now Borisjuk et al. have identified the first such sequence in plants and have shown that it increases the copy number and expression of adjacent heterologous genes. To identify the amplification-promoting sequence (aps), they zeroed in on a region of plant chromosomes that seemed prone to spontaneous amplification, and found a domain with homology to the A+T-rich tracks and autonomously replicating sequence consensus sequences found in mammalian amplification-stimulating DNA elements. When placed next to the genes for an herbicide resistance gene and GFP, the sequence significantly, though variably, increased the genes' copy numbers and expression, and in the case of the herbicide resistance, enhanced the phenotype as well. The effects were stably inherited, suggesting applications in agriculture and pharmaceutical production in crops (see p. 1303).