mr. speaker , we do not know yet , but the possibility is very real that stem cell research may be the greatest breakthrough in the history of science .  there are deep and profound moral and philosophic issues surrounding the research , but our government should be very cautious about coming down on the wrong side of science , especially when the scientific endeavor is designed to lengthen and ennoble life .  it has been suggested here today that no breakthrough therapies have yet been developed with stem cell research .  this is simply not the case .  using , for example , the microenvironment of human embryonic stem cells , dr .  mary hendricks and her team of researchers at chicago 's memorial research center have developed a methodology to slow the aggressive properties of metastatic cancer cells .  how in heaven 's name can we deny the promise of such research ?  there is consensus at this time in this body and in the research community that scientists should not play god in attempting to clone human beings , but we are at a stage of human existence where there is a practical possibility that a blastocyst that would otherwise be thrown away as waste can , in a petri dish , be used to help solve these incredible diseases , from alzheimer 's to parkinson 's to diabetes to cancer .  if one believes that life matters , the balance of judgment should be to carefully open the door , as this bill , led so beautifully by my good friends the gentleman from delaware ( mr. castle )  and the gentlewoman from colorado ( ms. degette )  , does .  not to open the door is to put our heads in the sands and foreclose the prospect of a better life for many , many americans .  