Complex sentence: Hwang claimed he and his team had extracted stem cells from cloned human embryos, however further examination of the cells' chromosomes show the same indicators of parthenogenesis in those extracted stem cells as are found in the mice created by Tokyo scientists in 2004.
Split into simpler sentences: Hwang claimed he and his team had extracted stem cells from cloned human embryos. However, further examination of the cells' chromosomes shows the same indicators of parthenogenesis in those extracted stem cells as are found in the mice created by Tokyo scientists in 2004.