BMP4 and tuberculosis: Subsequently, Yu et al. (2011) noted that, in a defined culture medium developed specifically for maintaining hESC in a pluripotent state and containing relatively high concentrations of FGF2 (mTeSR medium) (Ludwig et al. 2006), FGF2 signaling through the MEK/ERK signaling pathway negated the effects of BMP4 in promoting TB differentiation.