ER is generally present in which cells?

ER is Endoplasmic Reticulum and is generally present in all differentiated eukaryotic cells.
The endoplasmic reticulum (ER) is a highly convoluted, netlike meshwork that extends throughout the cytoplasm.
ER plays a crucial role in the synthesis, modification, transport, and degradation of membrane and secretory proteins, and is the site for biosynthesis, processing, and transport of several lipids, and regulation of cytosolic calcium levels.