KRAS and neoplasm: There was an increase in the wild-type Kras mRNA levels in tumors treated with MSC exosomes loaded with the plasmid Cas9/KrasG12D sgRNA1 (Fig S6B), which may be attributed to a reduction in tumor cells harboring mutant Kras and an increase in non-tumorigenic cells expressing wild-type Kras. Cas9 was detectable at the mRNA level in the subcutaneous tumors from the group that received exosomes + Exo-Fect + KrasG12D sgRNA1 (P < 0.05), Exo-Fect + KrasG12D sgRNA1, and exosomes + Exo-Fect + vector control relative to the group that received exosomes + Exo-Fect alone (Fig 3E).