IHC Scoring for RAB3C/Dystrophin Expression in CRC

We devised a four‐point staining‐intensity scoring system to determine the RAB3C/dystrophin expression in the CRC TMA specimens, and the staining intensity scores ranged from 0 (no expression) to 3 (high expression). We classified the results into two groups according to the intensity and extent of the staining: in the low‐expression group; either no staining was present (staining intensity score = 0), or we detected positive staining in fewer than 10% of the cells (staining intensity score = 1); in the high‐expression group, positive immunostaining was present in 10–30% of the cells (staining intensity score = 2), or in more than 30% (staining intensity score = 3). The extent of staining was scored by the percentage of positive cells (0–100%). The final IHC scores (0–300) were obtained by staining intensity score multiplied by the percentage of positive cells. All cases were divided into two groups according to the final IHC scores and processed 50% cutoff. Low IHC expression level was defined as a score less than 150 and a score more than 150 included and 150 itself was defined as high expression. Two pathologists reviewed and independently scored the IHC staining results [30 (link)]. The detailed process and classification are introduced in our previous articles [22 (link)].