Fate of breast milk microvesicles after endocytosis by target cells. After caveolar endocytosis, microvesicles translocate Arf1, Rab1 and SNARE proteins to the outer surface of the vacuolar membrane by a syringe-like mechanism. These proteins help the microvesicles to pass from caveola to the endoplasmic reticulum and fusion of the vacuoles with ER. In ER, decoating of the microvesicular membrane occurs with the help of Hsp 70 and cyclophilin A and the released RNA is translocated into the nucleus directly together with reverse transcriptase (RT). In the nucleus, the linear copy of the microvesicular RNA is inserted into chromosomal DNA with the aid of cellular endonuclease and transcribed into a double-stranded DNA by the microvesicular RT. New DNA achieves the status of a cellular gene and replicated by cellular enzymes in concert with chromosomal DNA as in nonretroviral retrotransposons.