B-CLL cells express the activities of both μ- and m-calpain.

Lysates of B-CLL cells of 4 patients (B-CLL 1 through 4) were prepared in either lysis buffer (L) or PBS (P) as in “Patients, materials, and methods” and tested by casein zymography. A mixture of 0.1 μg each of commercial μ- and m-calpain was processed alongside and served as activity standard (std). The activity of m-calpain can only be seen in the lysates prepared in PBS in which the activity of μ-calpain also is relatively enhanced.