A long-lasting recombinant human albumin-linker-erythropoietin (EPO) is a human albumin gene fused to the N-terminal of EPO with a (GGSGG)(n)-repeated linker inserted between albumin and EPO. Albumin-EPO fusion genes were co-transfected with the dhfr gene. Albumin-EPO fusion protein has three kinds of sub-types (IALE, AD2LE, AD1LE). Albumin-EPO fusion protein was quantified with human EPO ELISA. The in vitro efficacy of albumin-EPO fusion protein was estimated using F-36E cell, and in vivo efficacy of albumin-EPO fusion protein was estimated using normocythemic mice (B6D2F1). We also determined the in vivo half-life in a Sprague-Dawley rat. A PLA program analysis result demonstrated that the albumin-EPO fusion protein IALE is about 7.8-fold more potent than rHuEPO in increasing the hematocrit of normal mice. (C) 2009 Elsevier Inc. All rights reserved.