PIK3CA/PIK3CD increases with relapse in MCL. (A) Gene expression of the PI3K class IA isoforms compared with 2 tonsil controls (gray). Serial biopsies from the same patient are in the same color (B) western blot showing very weak expression of p110β and a clear increase in MCL p110α compared with tonsil while p110δ protein expression in MCL is similar to tonsil controls. Increase in p110α with relapse is apparent in 2 out of 4 serial biopsies (C) Dot plot showing a significantly higher PIK3CA/PIK3CD ratio in all relapsed samples compared with matched diagnostic samples and tonsil controls.