So, par4 doesn't kill all typees of cancer cells, but maybe because it interfers with signaling that promotes tumor growth it could help stop all types of cancers?
http://www.nyas.org/annals/annalsExtra.asp?annalID=34the new york academy of science says
"Par-4 does not kill all types of cancer cells. In cancer cells that resist Par-4, such as hormone-dependent tumors, there is sufficient PKA to allow phosphorylation to take place, but Par-4 is still kept out of the nucleus, meaning the cell survives."
Tumors in mice regressed quickly after treatment
"Par-4 also works in other ways. Previous work showed that Par-4 can suppress tumors by interfering with signaling that promotes tumor growth. In one experiment, when Par-4 was purposely overexpressed in cancer cells, they were prevented from forming colonies in a soft agar medium. In another, tumors were started in mice and allowed to grow. Then the tumors were injected either with Par-4 adenovirus (a viral vector delivery system), or with a control viral vector. After about three weeks, all twenty of the tumors injected with Par-4 shrank markedly, while the other tumors continued to grow apace."
"The researchers named the region of Par-4 responsible for singling out cancer cells the Selective Apoptosis of Cancer (SAC) domain. The protein is being developed as a potential therapeutic agent against an array of cancers, not just tumors of the prostate. Says Rangnekar, "The best part is that despite the apoptotic effect in cancer cells, neither the SAC domain nor Par-4 induces apoptosis in normal cells—implying that treatment should be non-toxic and safe." Also, the fact that Par-4 targets cancer in different ways provides multiple opportunities for drug development."