In a cancer study, the heterogeneous nature of a cell population creates a lot of challenges. Efficient determination of the compositional breakup of a cell population, from gene expression measurements, is critical to the success in a cancer study. This paper presents a new model for analyzing heterogeneity in cancer tissue using Markov chain Monte Carlo (MCMC) algorithms; we aim to compute the proportion wise breakup of the cell population on a GPU. We also show that the model computation time does not depend on the input data size, because the computation required to estimate the compositional breakup are parallelized. This model uses qPCR (quantitative polymerase chain reaction) gene expression data to determine compositional breakup in the heterogeneous cell population. We test this model on synthetic data and real-world data collected from fibroblasts. We also show how well this model scales to hundreds of gene expression data.