Thermo p21 Antibody (701151) Never Works

I tested p21 expression level in Huh7 cells. After treating doxorubicin, p21 is up-regulated, which is confirmed by RT-qPCR. Compared to the p21 antibody of Santa Cruz product, Invitrogen (701151) never gives a correct size of band. p21 expression was hard to detect even with well-published p21 antibody of Santa Cruz - I had to expose it quite a long time over 30 min to detect the signal. But it worked. Anyways, I was very disappointed with the quality of p21 rabbit mAb sold by Thermo. The product webpages shows a very nice 21kDa band of cell immunoblot results. I don't understand how they got the nice images.