"rps21 promoters and beta-actin and uses thereof." the invention refers to the isolation of new promoters of ribosomal protein (rps21) and ribosomal protein uses. In particular, this invention characterizes nucleotide sequences for R lt;225 gt;-actin'rodent promoters including hamster, mouse and mouse, and rps21 hamster."promotores rps21 e beta-actina e usos destes". a invenção refere-se ao isolamento de novos promotores de s21 (rps21) de proteína ribossômica e usos destes. em particular, esta invenção caracteriza seqüências de nucleotídeo para promotores de <;225>;-actina de roedor incluindo, hamster, rato e camundongo, e rps21 de hamster.