mice lacking the ci-mpr die at day 15 of gestation due to cardiac hyperplasia. the mice suffer from abnormal growth because they are unable to regulate the levels of free igf-ii (insulin-like growth factor type ii). death of the mice can be prevented if the igf-ii allele is also knocked out. further analysis of the embryos also showed that they display defects in the targeting of lysosomal enzymes as they have an increased level of phosphorylated lysosomal enzymes in their amniotic fluid. approximately 70% of lysosomal enzymes are secreted in the absence of the ci-mpr – this suggests that the cd-mpr is unable to compensate for its loss.