IE1-72 rather than IE2-86 was responsible for p21 downregulation in IE2-86 siRNA-treated HEL cells infected with HCMV. (A) Western blot demonstrating the levels of IE1-72, IE2-86, p53, and p21 in HCMV-infected HEL cells harvested at the indicated times postinfection. (B) Western blots demonstrating levels of IE1-72, IE2-86, p53, and p21 at 16 hpi in mock-infected HEL cells (lane 1), uninfected HEL cells pretreated with IE2-86 siRNA (lane 2), UV-treated HEL cells (lane 3), HCMV-infected HEL cells (lane 4), and HCMV-infected HEL cells that were pretreated with siRNA (lane 5). (C) Western blots demonstrating levels of IE1-72, IE2-86, p53, and p21 at 16 hpi in mock-infected HEL cells (lane 1), uninfected HEL cells pretreated with siRNA-Cy3 (lane 2) and IE1-72 siRNA (lane 3), HCMV-infected HEL cells (lane 4), HCMV-infected HEL cells that were pretreated with siRNA-Cy3 (negative control) and IE1-72 siRNA (lanes 5 and 6), and UV-treated HEL cells (lane 7).