Firefly systematics , as with many insects, are in a constant state of flux, as new species continue to be discovered. The five subfamilies listed above are the most commonly accepted ones, though others, such as the Amydetinae and Psilocladinae, have been proposed. This was mainly done in an attempt to revise the Lampyrinae , which bit by bit had become something of a " wastebin taxon " to hold incertae sedis species and genera of fireflies. Other changes have been proposed, such as merging the Ototretinae into the Luciolinae , but the arrangement used here appears to be the most frequently seen and stable layout for the time being. Though most groups appear to be monophyletic , some (., the tribe Photinini ) are perhaps better divided.
Several years ago, a PNAS paper reported that digoxin blocked tumor growth in mice xenotransplanted with several types of human cancer cells [ 17 ]. The authors observed that digoxin prolonged tumor latency and inhibited tumor xenograft growth in mice when treatment was initiated before the implantation of P493-Myc, P493-Myc-Luc, PC3, and Hep3B cells. Digoxin also arrested tumor growth when treatment was initiated after the establishment of PC3 and P493-Myc tumor xenografts [ 17 ]. Based on the observations of Gupta and colleagues [ 29 ] and on the plasma levels of digoxin in cardiac patients, we discussed the fact that the potent anticancer effects induced by digoxin in mice harboring human cancer cells [ 17 ] were not relevant to the treatment of human cancer and these anticancer effects were probably due to interspecies differences in sensitivity [ 25 ]. In other words, the marked reduction in tumor growth induced by digoxin in mice xenografted with human cancer cells was probably caused by the ability of cardiac glycosides to selectively kill human cells versus rodent cells rather than by their ability to selectively kill cancer cells versus normal cells. Perne et al. [ 22 ] later reported experimental data that further supported this idea. Despite these and other reports [ 24 , 26 ], numerous publications containing this probable experimental artifact continue to appear in the scientific literature.