The rough endoplasmic reticulum is directly continuous with the nuclear envelope and is thought to have evolved simultaneously with the nucleus in early cells. Since they are physically connected, the nucleus has direct access to many chemical compounds present in the endoplasmic reticulum cisternal space, eliminating the necessity of transport vesicles, which are employed to deliver chemicals to other organelles within the cell. The close association between the ER and the nucleus is also advantageous for communication between the two organelles, enabling them to share information very quickly and efficiently. The pig kidney cells appearing in the digital video sequences in this section were labeled with mEmerald fused to an ER targeting signal and mCherry fused to C-Src.