We have studied the influence of hydrostatic pressure on the light emission from cubic In0.1Ga0.9N. A qualitative difference between pressure dependence of photoluminescence peak energies for cubic and wurtzite symmetry InGaN/GaN quantum wells (QWs) was found. Cubic samples revealed magnitude of dEE/dP of 26-30 meV/GPa, practically independent of the QW width. Previous studies of the hexagonal InGaN/GaN structures showed that with increasing QW width dEE/dP changed between about 30 meV/GPa and 0 meV/GPa. This different behavior of two types of QWs can be explained by the lack of built-in electric field (along growth direction) in case of cubic structures. To describe pressure evolution of the optical transitions in cubic InGaN/GaN QWs and thick epitaxial layer, we use a simple k×p model based on the linear theory of elasticity. To reproduce the experimental data, it is necessary to invoke presence of In-rich fluctuations in the cubic In 0.1Ga0.9N samples.