HSPB1 and ovarian cancer: Importantly, type I collagen, the most abundant collagen in the tumor microenvironment, did not increase the total expression nor phosphorylation of HSP27 (at S78/82) in contrast to COL11A1 (Figure 1G), suggesting that an increase of HSP27 expression and phosphorylation might be specific to COL11A1 in ovarian cancer cells.