Once identifying that Vpx treatment increased late reverse transcription products but did not lead to the accumulation of 2-LTR products or productive infection, the Cimarelli group concluded that MLV is restricted not only by SAMHD1-mediated low dNTPs in these cell types but also by the lack of vDNA nuclear import [131,133,134,135]. This evidence concerns the gene SAMHD1 and infection.