lately I did 3 Western Blots using chick embryo retina cell culture as an experimental model. I used the Sigma´s anti-CB1 receptor produced in Goat and at evey blot a 55-58 kDa band is being recognized, but in the datasheet it is written that it recognizes an appox. 45 kDa band. Is it possible that a variation is occuring because of the animal model used in my experiments?