A, analysis of rat tissues and rodent cell lines. Amounts of total protein represented in each lane are indicated above figure. B, detection of MLCKs in smooth and non-muscle tissues. Between 50–100 μg (smooth muscle tissues) and 100–175 μg (non-muscle tissues) total protein are represented in each lane. Blot is overexposed to detect expression of 208-kDa protein. C, analysis of muscle-derived and non-muscle cultured cell lines. Cell extracts prepared either from non-muscle (REF, COS, CEF (chicken embryo fibroblast), HUVEC (human umbilical endothelial), or muscle-derived cell lines (A10, AT1, and AT2) were examined. 50 μg of total protein is represented in all lanes except HUVEC, AT1 and AT2 (25 μg each). Positions of molecular weight markers and MLCKs are indicated at the left side of the figure.