Evidence for the presence of non-muscle actin in LW13K2 rat neoplastic cells.

It was demonstrated that I-bands in cultured cardiac muscle cells and non-interrupted fibrils in smooth muscle cells, irrespective of phenotypic state and number of subculture, stained with an antibody directed against native actin from chicken gizzard smooth muscle, but that non-muscle cells in the same cultures did not stain. Neoplastic rat LW13K2 cells, whether confluent or subconfluent, did not stain with the same muscle-actin antibody. This is by no means evidence of a non-muscle origin of LW13K2 cells. However, it does show that these cells express in culture an actin which is not the same as that in muscle cells, and consequently that it can be used as a source of non-muscle actin.