Description_x000D_ Biochem/physiol Actions_x000D_ PKS21004 is highly selective, potent and reversible inhibitor of the Plasmodium falciparum proteasome (Pf20S) β5 subunit. It is not active against mammalian c-20S and i-20S proteasome subunits. PKS21004 is effective against erythrocytic, sexual, and liver-stage parasites. Also it is active against parasites resistant to current antimalarials, and strains from patients in Africa.