In addition, dyes (<10 kDa) and horseradish peroxidase (HRP) (44 kDa) taken up by host cells via endocytosis have been found to enter the cyst matrix and bradyzoites within in vitro cysts, whereas larger proteins such as bovine serum albumin (BSA) (65 kDa) and transferrin (80 kDa) were observed only around the cyst wall (11, 15). This evidence concerns the gene ALB and cyst.