SMAD4 and cancer: Cancer cells also displayed significant moderate to strong relationships between cytoplasmic and nuclear levels for several proteins: p-ERK (ρ = 0.72, p < 0.001), p-p38 (ρ = 0.56, p = 0.004), T308p-PKB (ρ = 0.52, p = 0.007), SMAD4 (ρ = 0.63, p < 0.001) and PTEN (ρ = 0.87, p < 0.001).