PTPA and lung adenocarcinoma: Three translational studies support such a role of the MID1/α4/PP2A complex: (i) a study on colorectal cancer, pointing towards MID1 as a metastatic gene and marker for poor survival [49], (ii) a study, which demonstrated that α4, the direct binding partner of MID1, is expressed universally in advanced lung adenocarcinomas and that its overexpression is significantly related to outcome [50], and (iii) a study, which shows that the expression and activity of PP2A is down-regulated in castration resistant prostate cancer cells [51].