To study an oncogene called c-Abl, you isolate total protein from normal cervical cells and from HeLa cells, which is a cervical cancer tissue culture cell line. You separate the proteins by denaturing gel electrophoresis and perform a western blot with an antibody that recognizes c-Abl, followed by a secondary antibody with a chemiluminescent label. The results are shown to the right. For each sample you see 238 a different major band (indicated by arrows) detected by the antibody. a) What does the difference in band position in the gel tell you about c-Abl in the two ’17 extracts? b) What does the difference in band intensity tell you about c-Abl in the two extracts? c) Was a blocking step included in the western blot procedure? How do you know?