Figure 4. Cardiac myocyte Ca²⁺‐handling proteins in mouse mammary tumor virus–polyomavirus middle T antigen (MMTV‐PyMT)− and MMTV‐PyMT+ mice—phospholamban (A); SERCA2a (sarcoplasmic or endoplasmic reticulum calcium 2 ATPase) (B); phosphorilated phospholamban (p‐phospholamban) (C); sodium/calcium exchanger (NCX) (D); and SERCA2a/phospholambam ratio (E).

Western blot bands are shown for each protein. In the MMTV‐PyMT+ mice, phospholamban protein expression was increased (P=0.011) and SERCA2a protein expression was not different between the MMTV‐PyMT+ and MMTV‐PyMT− groups (P=0.165). SERCA2a/phospholamban ratio was reduced in the MMTV‐PyMT+ mice (P=0.007). p‐Phospholamban and NCX protein expression were decreased (P=0.038 and P=0.017, respectively) compared with MMTV‐PyMT− mice. Mann‐Whitney test. Values are expressed as medians and interquartile ranges (IQRs). Animals per group: 7 MMTV‐PyMT− and 7 MMTV‐PyMT+.