lt;bgt;Myogenlt;/bgt; and lt;bgt;GlaxoSmithKlinelt;/bgt; (GSK) recently formed a two-part collaboration in the field of pulmonary arterial hypertension (PAH), in which Myogen is licensing to GSK the ex-US commercialisation rights for ambrisentan, which is currently in Phase III development for PAH. Myogen is also to market and distribute GSK's Flolan#174; (epoprostenol sodium) - a PAH drug nearing the end of its life cycle - in the US. This feature discusses the negative reaction the deal has provoked from the investment community, a not uncommon view being that Myogen has given away a sizeable share of the future profits from one of its key pipeline drugs in return for a mediocre sum.