rhHAPLN1 inhibits PDGF-BB-induced de-differentiation of HASMCs. (A) Expression levels of smooth muscle-specific markers and endogenous expression levels of HAPLN1 in HASMCs cultured in SMC differentiation media for 6 days, with or without the addition of PDGF-BB. CON: Cells that were not incubated in SMC differentiation medium; Untreated: Cells that were not treated with PDGF-BB; PDGF-BB: Cells that were treated with 10 ng/ml PDGF-BB. (B) Expression levels of smooth muscle-specific markers in HASMCs cultured in SMC differentiation media for 6 days, with or without the addition of rhHAPLN1. Untreated: Cells that were not treated with rhHAPLN1; rhHAPLN1: Cells that were treated with 20 ng/ml rhHAPLN1. (C) Expression levels of smooth muscle-specific markers determined by western blots. GAPDH was used as a positive control. Cells were exposed to 10 ng/ml PDGF-BB for 48 h with or without the indicated concentrations of rhHAPLN1. P-values indicated by # were calculated relative to control or untreated cells, whereas P-values indicated by * were calculated relative to untreated or PDGF-BB treated cells. * or # indicates P < 0.05, ** or ## indicates P < 0.001, *** or ### indicates P < 0.0005, and **** or #### indicates P < 0.0001 (N = 3 per group).